Behavioral and Physiological Ecology and Community ...

KU ScholarWorks | The University of Kansas Central American Theses and Dissertations Collection

Behavioral and Physiological

Ecology and Community

Structure of Tropical Cockroaches

(Dictyoptera: Blattaria)

Professor in ChargeWilliam J. Bell

Committee MembersCharles Michener

Rachel Jander

by Coby Schal

B. S., University at Albany SUNY, 1976

The University of Kansas has long historical connections with Central America and the many Central

Americans who have earned graduate degrees at KU. This work is part of the Central American Theses

and Dissertations collection in KU ScholarWorks and is being made freely available with permission of the

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BEHAVIORAL AND PHYSIOLOGICAL ECOLOGY AND COMMUNITY

STRUCTURE OF TROPICAL COCKROACHES

(DICTYOPTERA: BLATTARIA)

by

Cob y Schal

B.S., State University of\ New York at Albany, 1976

Submitted to tfxe Department of Entomology and the Faculty o f the Graduate School of the Universi ty of Kansas in part ia l fu l f i l lment o f the requirements for the degree of Doctor of Philosophy

Chairman

JL •y y y .

V Á

Dissertation defended

December 17, 1982

RDD117 ^3t.7M

2

ACKNOWLEDGEMENTS

Each chapter i s f o l l owed by a l i s t o f persons and o r g a n i z a t i o n s who

cont r ibuted to var ious s tages o f t h i s e f f o r t .

I am most g r a t e f u l to Dr. Wi l l i am J . B e l l for h i s encouragement,

i n t e r e s t , and f i n a n c i a l support during my graduate s t u d i e s . I a m

indebted to Dr. Frank W. F isk for i d e n t i f y i n g vouchers o f the

B l a t t a r i a c o l l e c t i o n and l ead ing a s t imula t ing workshop a t the

U n i v e r s i t y o f Kansas on the taxonomy o f cockroaches .

I a l s o wish to thank members o f my graduate committee ( D r s . K.B.

Armi tage , W.J. B e l l , R. Jander, C D . Michener , and 0. Tay l o r ) which

d i r e c t e d and reviewed va r i ous d r a f t s o f t h i s work.

F inanc ia l support was provided in par t by the Beamer Fund and the

Graduate School o f the Un i v e r s i t y o f Kansas, the s o c i e t y o f Sigma Xi ,

and the Nat ional Science Foundation to which I am e s p e c i a l l y t h a n k f u l .

I a l s o wish to thank P a t r i c i a Estes f o r her encouragement and

thought fu l suppor t .

F i n a l l y , I thank my parents who withstood years o f "cockroach t a l k "

to see t h i s document. I hope t h i s a t l a s t r e s o l v e s t h e i r ques t ion o f

"Why not medical school ? "

3

TABLE OF CONTENTS

Page

I Acknowledgements 2

I I L i s t o f Tables 6

I I I L i s t o f I l l u s t r a t i o n s 7

IV CHAPTER 1

Introd uction

A. C l a s s i f i c a t i o n o f B l a t t a r i a 10

B. Habitat pre ferences and microhabitat s e l e c t i on . . . 1 1

C. Object ives o f present research 15

V CHAPTER 2

Notes on New Species o f Epilamprine Cockroaches from Costa Rica and Panama ( B l a t t a r i a : B laber idae )

A. Abstract 16

B. Introduct ion • . 1 7

C. Key to spec ies o f the Car inulata Group 18

D. Epilampra i n v o l u c r i s Fisk and Schal , New Species • 19

E. Epilampra b e l l i Fisk and Schal, New Species 2 3

F. Epilampra u n i s t i l a t a Fisk and Schal , New Species . 2 5

G. Epilampra r o th i Fisk and Schal , New Species 2 7

H. Acknowledgements • 3 1

VI CHAPTER 3

V e r t i c a l Community Structure and Resource U t i l i z a t i o n o f Trop ica l Rain-Forest Cockroaches

A. Abstract 41

B. In trod uction 42

4

Page

C. Ma te r i a l s and methods 44

D. Results 49

1. A c t i v i t y pa t t e rns and perch t ypes 49

2. I n t e r s p e c i f i c s t r a t i f i c a t i o n and niche met r i cs 50

3. I n t r a s p e c i f i c v e r t i c a l s t r a t i f i c a t i o n 53

4. Die l a c t i v i t y 54

5. Habitat complex i ty and height pre fe rence 56

6. Ind i v idua l v a r i a t i o n s in perch height 57

7. V is ion and he ight s e l e c t i o n 57

E. Discussion 58

1. Why perch ? 58

2. Morphology and perching 62

3. Temporal p a r t i t i o n i n g 64

4. Niche me t r i c s and compet i t ion 66

F. Acknowledgements 68

V I I CHAPTER 4

I n t r a s p e c i f i c V e r t i c a l S t r a t i f i c a t i o n as a Mate-Finding Mechanism in Trop ica l Cockroaches

A. Abstract 91

B. Introduct ion 92

C. Results and d iscuss ion 93

. D. Acknowledgements 97

V I I I CHAPTER 5

Eco l og i ca l Cor re l a t es o f Paternal Investment o f Urates in a Trop ica l Cockroach

A. Abstract 104

B. I n t r o d u c t i o n

C. R e s u l t s and d i s c u s s i o n

D. Acknowledgements

REFERENCES CITED

6

LIST OF TABLES

Number Page

2-1 Measurements o f adult Epilampra i n vo luc r i s 33

2-2 Measurements o f adult Epilampra b e l l i 34

2-3 Measurements o f adult Epilampra u n i s t i l a t a 35

2-4 Measurements o f adult Epilampra ro th i 36

3-1 Comparison o f t rap catch at four he ights 69

3-2 Comparison o f i n d i v i d u a l and spec i es v a r i a t i o n s

in height pre f e rences 70

3-3 Time that exper imental Epilampra i n v o l u c r i s males

remained on a l e a f a f t e r r e l e a s e 71

5-1 Fate o f l abe l ed hypoxanthine in jec ted in to males 113

7

LIST OF ILLUSTRATIONS

Number Page

2-1 Male g e n i t a l i a o f Epilampra s p e c i e s 37

2-2 A. Male Epilampra r o t h i , hab i tus o f dark form 39

B. Vent ra l aspect o f the d i s t a l par t o f the abdomen

o f Epilampra u n i s t i l a t a 39

C. Vent ra l aspec t o f the d i s t a l par t o f the abdomen

o f Epilampra r o t h i 39

3-1 V e r t i c a l d i s t r i b u t i o n s o f s p e c i e s , s e x e s , and l i f e -

s t a g e s o f cockroaches 72

3-2 V e r t i c a l v e g e t a t i o n p r o f i l e o f the study area 75

3-3 R e l a t i o n between v e r t i c a l o v e r l a p and o v e r l a p

c o r r e c t e d f o r the a v a i l a b i l i t y o f perches . 77

3-4 R e l a t i o n s h i p between s p e c i e s mean h e i g h t

and v e r t i c a l o v e r l a p . . . . 79

3-5 R e l a t i o n s h i p between s p e c i e s mean he i gh t and

v e r t i c a l o v e r l a p c o r r e c t e d to account f o r perch

a v a i l a b i l i t y 81

3-6 Dendrogram o f e c o l o g i c a l s i m i l a r i t y o f s p e c i e s and

consexua l s based on o v e r l a p s in v e r t i c a l d i s t r i b u t i o n s . . . . 83

3-7 R e l a t i o n between mean he i gh t and v e r t i c a l breadth

f o r s p e c i e s and sexes 85

3-8 R e l a t i o n between mean h e i g h t s and the d i f f e r e n c e

in mean h e i g h t s o f c o n s p e c i f i c females and males 87

8

Number Page

3-9 D i e l a c t i v i t y o f cockroaches in the f i e l d and in an

outdoor in sectary . . 89

4-1 Temperature p r o f i l e s o f a t y p i c a l 24-hour per iod in

the d ry season (10 A p r i l 1980) 98

4-2 Wind p r o f i l e s fo r day and night cond i t i ons in the

d ry season 100

4-3 Ti tanium t e t r a c h l o r i d e as a po int source for smoke plumes • 102

5-1 A. Copulating pair o f Xes tob la t ta ham ata 115

B. Pos t -copu la tory f eed ing behavior 115

C, Male Xestob la t ta hamata feeding on b i rd droppings . . . . . 115

5-2 Whole body and ovar ian ur ic acid contents o f Xestob la t ta

hamata females during one ovar ian c y c l e 117

9

CHAPTER 1

In t roduc t i on

In the i n t r o d u c t i o n to t h e i r t r e a t i s e on the b i o t i c a s s o c i a t i o n s o f

cockroaches , c i t i n g some 1700 r e f e r e n c e s , Roth and W i l l i s (1960)

concluded t h a t , "our d e t a i l e d knowledge o f cockroaches i s based on

s tud i es o f few d o m i c i l i a r y pes ts t h a t man at tempts to e r a d i c a t e .

Comparable s t u d i e s o f the b ionomics o f the l e s s we l l known s p e c i e s

should add much va luab l e in format ion to our knowledge o f t h i s anc i en t

g r oup . " In the years s ince the t r e a t i s e , and to a l a r g e e x t en t because

o f R o t h f s continued r e s e a r c h , the cockroach has become a "wh i t e r a t " o f

i n v e r t e b r a t e b i o l o g i c a l r e s e a r c h . Y e t , the gloomy p i c t u r e presented

above has changed l i t t l e . Of the 109 s t u d i e s l i s t e d in the 1980

B i o l o g i c a l Abs t rac t s under the heading " c o c k r o a c h " , 55% deal wi th

p h y s i o l o g i c a l a spec t s and/or c o n t r o l o f Pe r ip l ane ta americana or

B l a t t e l l a germánica . The o the r 49 r e p o r t s examine one or s e ve ra l s p e c i e s

maintained in l a b o r a t o r y c u l t u r e s . Of t h e s e , 65% address deve l opmenta l ,

g e n e t i c , c e l l u l a r , or molecu lar q u e s t i o n s . Me thodo l o g i c a l ,

p s y c h o l o g i c a l , and papers d ea l i ng p r i m a r i l y with o ther animal groups

comprise the bulk o f the remaining 17 papers . With few e x c e p t i o n s , t h e

behav i o ra l and e c o l o g i c a l s tud i e s a r e conce ived and implemented in the

l a b o r a t o r y . These s t a t i s t i c s are r e p r e s e n t a t i v e o f o ther r ecent years

as w e l l . Our t o t a l e c o l o g i c a l in format ion on s e v e ra l spec i es which a r e

wel l s tudied in l a b o r a t o r i e s i s provided by the l a b e l s accompanying

museum spec imens . For i n s t a n c e , both Gromphadorhina por tentosa and

10

Nauphoeta c iné rea have been studied e x t e n s i v e l y with regard to the i r

soc ia l b ehav i o r , neurophys io logy , and endocr inology ( see Bel l and

Ad iyod i , 1981) . Y e t , our understanding o f t h e i r natural hab i ta t s and

e c o l o g i c a l a ssoc i a t i ons i s l im i t ed to vague geographic d i s t r i b u t i o n

da ta .

A. C l a s s i f i c a t i o n o f B l a t t a r i a

Cockroaches are placed in f i v e f am i l i e s comprising two major

p h y l e t i c l i n e a g e s separated on the bas i s o f reproduct i ve s t r a t e g i e s and

morphology ( M c K i t t r i c k f 1964) .

Members o f the p r i m i t i v e Cryptocercidae are oviparous and they are

p h y s i o l o g i c a l l y and e c o l o g i c a l l y s imi lar to t e r m i t e s . The B la t t idae are

a l so o v i pa r ous , producing egg cases f r e quen t l y ; embryogenesis proceeds

in the d iscarded ootheca. B l a t t e l l i d a e i s the l a r g e s t family with

members ranging from the b l a t t i d reproduct i ve mode to a s t r a t e gy

con f e r r ing g r ea t e r p ro t ec t i on on the deve loping embryos; the female may

r o t a t e and then ca r r y an ootheca e x t e r n a l l y (at tached at the g e n i t a l

pouch) u n t i l the young hatch. Females in the family Polyphagidae a l so

ca r ry the ootheca e x t e r n a l l y a f t e r r o t a t ing i t in a manner s imi lar to

some o f the b l a t e l l i d s . The most advanced forms occur in the l a r g e l y

t r o p i c a l Blaber idae . In a l l o f the Blaberidae the egg case i s ro ta ted

and r e t r a c t e d i n t e r n a l l y in to the uterus where embryogenesis o c curs .

Pseudo-v iv iparous Dip loptera punctata represents the most h i gh l y evo lved

s t r a t e g y wi th in the B laber idae . The imp l i ca t i ons o f these reproduct i ve

s t r a t e g i e s w i l l be discussed in r e l a t i o n to s p a t i a l d i s t r i b u t i o n s ,

communication and soc ia l behavior o f cockroaches.

11

B. Habi ta t p r e f e r e n c e s and m i c rohab i t a t s e l e c t i o n

Few s t u d i e s deal with cockroach hab i ta t p re f e r ences under natuara l

c o n d i t i o n s , a l though l a b o r a t o r y i n v e s t i g a t i o n s document p r e f e r ences f o r

temperature (Gunn, 193^, 1935; Gunn and Cosway, 1938; Edney e t a l M

1978; A p p e l , 1982 ) , humid i ty (Gunn, 1935; Gunn and Cosway, 1938; Edney

e t a l . , 1978; Appel , 1982) , l i g h t c o n d i t i o n s (Goustard, 1958; Crawford

and Cloudsley-Thorapson, 1971)» t ypes o f s h e l t e r s (Ber tho ld and W i l s on ,

1967; Mizuno and T s u j i , 1974 ) , and subs t ra t e ( Takag i , - 1979; Crawford and

Cloudls ley-Thompson, 1971) .

Gautier (1974a ,b) studied the s p a t i a l d i s t r i b u t i o n o f burrowing

b laber id nymphs in c a v e s . The number o f nymphs found in each 50 cm

square sample c o r r e l a t e d p o s i t i v e l y wi th both the depth and quant i t y o f

o rgan ic mat ter in the subs t ra t e s t e s t e d . Nymphs concentra te in zones in

the substratum where ba t guano, f r u i t , and t w i g s dropped by b a t s

accumulated. Nymphs are absent from zones o f dry s o i l , s t o n e s , or

pebb l es . There fo re the p o s i t i o n s o f ba ts in the c a v e , which determine

the placement o f guano, a re r e l a t e d to the h o r i z o n t a l d i s t r i b u t i o n o f

nymphs.

Cockroaches employ b ehav i o r a l s t r a t e g i e s to cope with adverse d e s e r t

c l i m a t e s . Aren i vaga and Polyphaga (Po lyphag idae ) avoid the heat and l ow

humidity o f the d e s e r t by a s s o c i a t i o n s wi th burrowing t u r t l e s and

rodents during the day (Roth and W i l l i s , 1960) . The r e l a t i v e humidi ty

ins ide kangaroo r a t burrows , f o r example, i s s e v e ra l f o ld higher than

that recorded on the d e s e r t sur face (Schmidt -Ne i l sen, 1949, in Roth and

W i l l i s , 1960 ) . Des iccated A. i n v e s t i g a t a can absorb water vapor from

12

the surrounding a i r at r e l a t i v e humid i t i es o f 82? or above (Edney,

1966) . R e l a t i v e humid i t i es o f 82% and above are a v a i l a b l e only 45 cm

below the sand surface (Edney e t a l . f 1974). Hence these microhab i ta ts

may prov ide cockroaches with a p r ed i c t ab l e source o f water .

The patchy d iurna l d i s t r i b u t i o n o f cockroaches near dese r t p lan ts

a l so can be explained by water r e l a t i o n s (Hawke and Far l ey , 1973; Edney

e t a l . f 1974 ) . Micorrhizae that coat adven t i t i ous r o o t s o f d e s e r t

shrubs ( H a r l e y , 1959) and conta in 35-38% moisture are found in gut

smears o f Arenivaga sp . These fungi are probably u t i l i z e d as sources o f

water as we l l as n u t r i e n t s . Arenivaga sp . i s never seen on branches or

l e a ves o f p l an t s above the d e s e r t f l o o r , and surface a c t i v i t y ceases i f

the temperature reaches 40° C (Hawke and Far l ey , 1973). By c o n t r a s t ,

adu l t males o f ^ i n v e s t i g a t a emerge above the sur face , perch on

bushes, and f l y to l i g h t s (Edney e t a l . , 1974).

Studies tha t d e l i n e a t e microhabi ta t pre ferences in f o r e s t

communities are l im i t ed to spec i es d e s c r i p t i o n s with q u a l i t a t i v e

in format ion on d i s t r i b u t i o n , l i f e h i s t o r i e s , and general hab i ta t s ( e . g . ,

B l a t c h l e y , 1920) , and c l a s s i f i c a t i o n o f h a b i t a t s based on s o i l t y p e s ,

d r a i n a g e , s l o p e , and f l o r a l composi t ions ( e . g . , Can t r a i l , 1943; F r i au f ,

1953) . Lawson's ( 1967) work i s a summary o f trapping data , but no

in format ion i s provided on the methods employed, types o f t raps used, or

the schedule o f t r app ing . Gor ton ' s ( 1980) study o f six wood cockroaches

( B l a t t e l l i d a e ) in Kansas examined v e r t i c a l and hor i zon ta l d i s t r i b u t i o n s ,

r e l a t i v e abundance, and seasonal v a r i a t i o n s in grassland and f o r e s t

h a b i t a t s .

The need for i n t ens i v e work on temperate cockroaches i s bes t

13

i l l u s t r a t e d by the con t ras t ing r e s u l t s o f these and other papers . For

i n s t ance , Lawson s t a t e d , on the b a s i s o f a few cap tures , tha t

11 Pa rcob la t ta b o l l i a n a was s t r i c t l y a grassland cockroach spec i es in

Kansas, and JP l a t a was f r e q u e n t l y in open woodlands." Gorton, on the

bas i s o f two " n o n f o r e s t " and 12 " f o r e s t " s i g h t i n g s c o n s i d e r s , the former

a f o r e s t s p e c i e s ; on the b a s i s o f 110 captures he found _P. l a t a most

commonly in p r a i r i e and d is turbed g rass l ands . Both s tud ies agree tha t

P. uh ler iana and JP^ v i r g i n i c a are f o r e s t s p e c i e s , but Fr iauf (1953)

found the l a t t e r o n l y in scrub h a b i t a t s . Unfor tunate ly , d i f f e r e n c e s

between the f i e l d s i t e s and methods preclude a d i r e c t comparison o f

these s t u d i e s .

Four spec i es o f Ectobius ( B l a t t e l l i d a e ) were observed by Morvan

(1972) in Br i t t any in the f o l l ow ing b io to p e s : JE lapponicus on

mesophilous heathlands under pine t r e e s , l i v i d u s along borders

between f o r e s t and mesophilous heath lands , dry heath lands , and edges o f

peat b o g s , JL_ panzer i on meso- and xerophi lous heathlands and E.

s y l v e s t r i s on mesophilous hea th lands , peat b o g s , and f o r e s t b o r d e r s .

Other data from Europe i n d i c a t e l o c a l i z a t i o n s o f _E^ lapponicus and E.

panzer i in deciduous f o r e s t . S t r i c t r e l a t i o n s h i p s between a g i v en

hab i t a t and any one o f these spec i e s are not e v i d e n t .

Other r e p o r t s o f m ic rohab i ta t s e l e c t i o n inc lude i n v e s t i g a t i o n s o f

s p e c i a l i z e d n i ches . Roth and W i l l i s (1960) reviewed a s soc i a t i ons o f

cockroaches with t e r m i t e s , a n t s , b e e s , wasps, and b i r d s . Although no

s tud ies attempt t o d e l i n e a t e p re f e r ences o f commensal cockroaches, much

informat ion i s a v a i l a b l e about the b i o t i c and phys ica l c h a r a c t e r i s t i c s

o f these m i c r o h a b i t a t s . Many cockroach commensals are r e s t r i c t e d to

14

the i r myrmecophilous or terraicophi lous h a b i t a t s , although other

occas ional or acc iden ta l a s soc i a t i ons were repor ted (Roth and W i l l i s ,

1960) . Commensal a s soc i a t i ons are no doubt the r e s u l t o f e c o l o g i c a l

convergence o f unrelated spec i e s on s imi la r mic rohab i ta ts (Chopard,

1924) .

Rott ing l o g s and loose boards o f f e r a microhab i ta t for many t r o p i c a l

and temperate s p e c i e s . Best studied i s Cryptocercus punctulatus

(Cryptocerc idae ) in the Appalachian mountains and in Oregon and northern

Ca l i f o rn ia in the U.S. (C leve land e t a l . , 1934; See l inger and

S e e l i n g e r , unpubl ished ) . Family groups o f a male , female , and nymphs

excavate in f a l l e n r o t t i n g l o g s which are used as food . Other

congeneres occur in s imi la r hab i t a t s in the Far East (Boby leva , 1975) *

Extensive work o f Cleveland e t a l . (1934) on t h i s cockroach and i t s

symbiot ic protozoans examines, among other t o p i c s , the geographica l and

microhabi tat d i s t r i b u t i o n o f punctulatus . Forested l o c a l i t i e s with

dense l e a f - l i t t e r prov ide a su i t ab l e coo l environment for C.

punctulatus, but " the main f ac to r ( c o n t r o l l i n g the d i s t r i b u t i o n o f t h i s

i n s e c t ) i s probably the e f f e c t o f temperature on i t s c e l l u l o s e - d i g e s t i n g

protozoa without which i t cannot e x i s t " (Cleveland e t a l . , 1934) .

Many spec ies have been c o l l e c t e d under loose bark o f l i v e or f a l l e n

l o g s , including North American spec i es o f Parcoblat ta ( s ee Roth and

W i l l i s , 1960). Schal and See l inge r (unpublished) noted that Capucina

pa tu l a j u v e n i l e s in Costa Rica were r e s t r i c t e d to these h a b i t a t s ,

whereas adul ts were o c c a s i o n a l l y seen on nearby f o l i a g e . Being

c r y p t i c a l l y co lored and d o r s o - v e n t r a l l y depressed, patula i s we l l

adapted for burrowing in c r e v i c e s .

15

C. O b j e c t i v e s o f p r esen t r e s ea r ch

My o v e r a l l g o a l was t o ga in i n s i g h t in to the d i s t r i b u t i o n a l e c o l o g y

o f some t r o p i c a l cockroaches and to r e l a t e e c o l o g i c a l pa t t e rns t o

i n t e r s p e c i f i c , i n t r a s p e c i f i c f and t r oph i c r e l a t i o n s among cock roaches .

Most cockroaches are t r o p i c a l . S tud ies o f temperate s p e c i e s concern

e c o l o g i c a l l y marg ina l ( u s u a l l y d o m i c i l i a r y ) s p e c i e s . T h e r e f o r e , t h i s

study o f some t r o p i c a l s p e c i e s i s a s t a r t f o r i n v e s t i g a t i o n s o f

cockroaches in the h a b i t a t s where they a re most abundant and d i v e r s e .

Chapter 2 i s a taxonomic t r ea tment o f t h r e e o f the common s p e c i e s a t

the La Se lva f i e l d s i t e , and a r e l a t e d spe c i e s from San V i t o , Costa

R ica . I t was e s s e n t i a l t ha t these s p e c i e s be named and t h e i r

p h y l o g e n e t i c r e l a t i o n s h i p s understood in order to record and understand

the b i o l o g i c a l i n f o rma t i on concern ing them.

Chapter 3 r e p o r t s the framework o f the r e s e a r c h . In i t I d e s c r i b e

the cockroach community and presen t data r e l a t i n g to perch he i gh t and

va r i ous n iche m e t r i c s . D i f f e r e n c e s in r e source u t i l i z a t i o n between the

major p h y l e t i c l i n e s are d iscussed .

In Chapter 4 I address the problem o f d i f f e r e n t i a l h a b i t a t

u t i l i z a t i o n by the sexes and examine i t s r o l e in m a t e - f i n d i n g .

Chapter 5 i s a study o f sexual s e l e c t i o n in one s p e c i e s . I t r e l a t e s

male c o n t r i b u t i o n o f u r a t e s t o females t o n i t r o g e n d e f i c i e n t

env i ronment . This study was p a r t o f a l a r g e r e f f o r t to r e l a t e s e x u a l l y

d i v e r g e n t h a b i t a t s to t r o p h i c d i f f e r e n c e s between males and f e m a l e s .

16

CHAPTER 2

New Species o f Epilamprine Cockroaches from Costa Rica and Panama

( B l a t t a r i a : B laber idae )

Four new spec i es o f Epilampra are descr ibed , Ej_ i n v o luc r i s and E.

b e l l i from Costa Rica, and E^ u n i s t i l a t a and ro th i from Costa Rica

and Panama. The f i r s t t h r e e , along with E^ ca r inu la ta (Saussure ) , are

designated as the Car inula ta Group of Epilampra *

17

INTRODUCTION

Several undescribed spec i es o f cockroaches were encountered in Costa

Rica and Panama in recent y e a r s . In t h i s chapter four new spec ies are

desc r ibed , and some b i o l o g i c a l notes g iven in order to f a c i l i t a t e future

s tud i e s . I f o l l o w Roth 's O 9 6 9 » 1970a,b, 1973) methods o f d i s s e c t i on

and preparat ion o f the g e n i t a l i a and h is system ( as der ived from

McKi t t r i ck , 1964) for naming the p a r t s . Roth (1970b) in h is study o f

the genus Epilampra Burmeister, 1838» discussed the c lose a f f i n i t i e s o f

Audreia She l fo rd , 1910, to Epilampra and the ambigu i t i es encountered by

other s p e c i a l i s t s (Hebard f 1920; Rehn and Hebard, 1927) r esu l t ing from

She l f o rd ' s cha rac t e r i z a t i on of Audreia. Consequently, Roth t rans fe r red

a l l the Audreia spec ies which he examined, except the t ype - spec i e s , A.

car inu la ta (Saussure ) , 1895» into e i the r Subgroup A o f his Burmeister i

Group or h i s monotypic Heusseriana Group o f Epilampra or to the genus

Poeci lod err h i s S t a l , 1874. Roth based h i s conclusions c h i e f l y on the

morphology o f the male g e n i t a l i a , not ing that the primary character used

by She l f o rd , the reduced subquadrate tegmina in both sexes , i s not

shared by a l l Audreia. For example, e xp l o r a t r i x Gurney has l a t e r a l

lobate tegmina, wh i l e A^ bromeliadarum Caudell and A._ c i c a t r i c o s a

(Rehn) are apterous . Three o f the spec ies described here share

characters o f the male g e n i t a l i a and l ack o f a l e f t s t y l e with A.

ca r inu la ta , y e t the nymphal co l o r pa t t e rns , where known, are t yp i ca l o f

Epilampra. I consider these four spec i es to comprise a new spec ies group

within the genus Epilampra.

The ho lotypes and a l l o t y p e s o f a l l four spec ies described here are

18

deposited in the Ohio State Un ivers i t y Entomology Museum. Paratypes are

divided about equa l l y between the Snow Entomological Museum, Univers i ty

of Kansas, and the F.W. Fisk c o l l e c t i o n .

Car inula ta Group

Adults usual ly shining reddish brown; tegmina usual ly shor t ,

subquadrate in both sexes (but may be f u l l l e n g t h ) ; sub-genita l p la t e o f

male asymmetric, s i n g l e r i g h t s t y l e ; hooked phal lomere, R2, s t ou t ,

without subapical i n c i s i o n , sheath proximal to base of R2 without row o f

slender setae noted for most Epilampra; s c l e r o t i z a t i o n o f l e f t

phallomere, L2d, d iagnos t i c for the group and spec ies within i t ; nymph

tan or g ray , numerous dark punctations as t yp i ca l for Epilampra,

Appearance of R2 in t h i s group very s imilar to R2 in Poec i l oder rh is ( as

defined by Roth, 1970a), but no Carinulata Group spec ies shows abdominal

t e rga l glands as noted for male Poeci lod e r r h i s .

KEY TO SPECIES OF THE CARINULATA GROUP

1. Adult f u l l y winged in both sexes u n i s t i l a t a , new spec ies

Adult with t iny wing rudiments and short subquadrate tegmina in both

sexes 2

2. Sna l l e r , l ength o f male under 14 mm, o f female under 18 mm

carinulata (Saussure)

Larger , length o f male 16-23 mm, o f female 22-28 mm 3

3. Male with f la t tened s c l e r o t i z a t i o n o f l e f t phallomere, L2d, L-shaped

and b lunt- t ipped ( F i g . 2 -1A ) ; female with l a t e r o - p o s t e r i o r angles

o f abdominal tergun 7 acute ; supra-anal p la te with very shal low

(0.15 mm deep) median notch i n v o l u c r i s , new spec ies

19

Epilamra i n v o l u c r i s Fisk and Schal , NEW SPECIES

F i g s . 2-1A, 2-1B, 2-1C

Male h o l o t y p e . Measurements in Table 2 - 1 . Head broad and f l a t ,

i n t e r o c u l a r d i s t a n c e nea r l y h a l f width o f head, d i s tance between white

o c e l l a r spots one th i rd width o f head; m a x i l l a r y palpus p a l e , d i s t a l

( f i f t h ) segment covered with gray m i c r o t r i c h i a e g i v i ng i t a v e l v e t y

appearance; segment 5 l onge r than 4, s l i g h t l y shorter than 3; mouthparts

l i g h t e r co lo red than reddish brown o f head and body; antennae brown,

shor ter than body. Pronotum convex , semic i rcu lar in o u t l i n e ,

l a t e r o - p o s t e r i o r ang les rounded, r i g h t and l e f t pos t e r i o r margins

s t r a i g h t , meeting a t obtuse ang le (160 d e g r e e s ) ; pronotum cover ing most

o f head; tegmina t runca t ed , one and a th i rd t imes as long as pronotum,

t h e i r l a t e r o - p o s t e r i o r ang les broad ly rounded, p o s t e r i o r margins nea r l y

s t r a i g h t , exposing 7 abdominal t e rga but cover ing t i n y wing rudiments ;

tegmina smooth, venat ion f e e b l y ind icated by l i n e s o f sha l low

punctat ions between s c a r c e l y e l e va t ed v e i n s .

Abdominal t e r g a , except tergum 7i bear acute sp ines a t

l a t e r o - p o s t e r i o r a n g l e s , smooth except fo r up t o 18 low l o n g i t u d i n a l

r i d g e s ( c i c a t r i c e s ) on d i s t a l quarter o f each tergum; t e r g a l g lands or

s p e c i a l i z a t i o n s not e v i d e n t ; supra-anal p la t e extends beyond sub-gen i ta l

Male wi th f l a t t ened s c l e r o t i z a t i o n o f l e f t phal lomere , L2d ,

hammer-head-shaped ( F i g . 2 -1D ) ; female with l a t e r o - p o s t e r i o r ang les

o f abdominal t e rga 3-7 a c u t e , s p i n e l i k e ; supra-anal p la t e without

median notch b e l l i , new spec i e s

20

p l a t e , broad ly rounded p o s t e r i o r l y with shallow ( 0 . 2 mm deep) median

notch; p l a t e reddish brown prox imal ly , d i s t a l ha l f near ly transparent

with scattered small raised black spo ts , each surrounded by a se ta l

socket; cercus l i g h t brown, f l a t t e n e d , s tout , apparently 10-segmented;

terminal segment f inger-shaped, b lack - t ipped . Geni ta l ia ( F i g s .

2-1A,B,C) s imi lar to those o f car inulata (Roth, 1970b, F i g s . 347-352) ;

hooked r i g h t phallomere (R2) smal l , s tout , blunt-t ipped except f o r

minute d i s t a l sp ine ; subapical inc is ion l a ck ing . R2 of holotype has

apparent s p l i t on outer circumference o f hook, but s p l i t lacking in

dissected paratypes . F la t s c l e r o t i z a t i o n o f l e f t phallomere (L2d)

blunt-t ipped and L-shaped as in ca r inu la ta , but membranous prepuce

r ead i l y v i s i b l e due to th ick cover ing o f mic ro t r i ch iae ; phallomere L1

with deep, we l l defined c l e f t , s e ta l brush l a ck ing .

Abdominal sterna smooth, transverse except pos te r io r margin o f

sternum 7 with sharp l a t e r a l emarginations at base o f each cercus , the

remainder broadly concave; sub-genita l p late with anter ior margin

broadly convex, pos te r i o r margin convex l a t e r a l l y , broadly emarginate

c en t ra l l y with simple (0 .5 mm) r i g h t s t y l e , l e f t s t y l e absent. Legs and

ventral body surface brown, l e s s reddish than dorsal sur face ;

ven t ro -ante r i o r margin o f f ront femur with 4 la rge spines separated by

row o f minute setae from 2 ap ica l sp ines ; vent ro -anter io r margins o f

mid- and hind femora with 4 spines plus apical sp ine , o f hind-femur with

4 spines on l y ; mid- and hind femora with dorso-apica l ( gen icu la r ) sp ine .

Tibiae f u l l y sp ined ; t a r s i with obvious p u l v i l l i on 4 proximal

tarsomeres, l a r g e arolium and simple symmetrical claws on f i f t h

tarsomere.

21

Female a l l o t y p e . External form and co lor s imi la r to those o f male

except as f o l l o w s : Tegmina with pos t e r i o r margins broadly rounded,

merging impercept ib ly with l a t e r o - p o s t e r i o r ang l e s ; tergum 7 with

l a t e r o - p o s t e r i o r ang les acute ; supra-anal p la te uniform reddish brown ,

lacking co l o r pat tern noted for t yp e , p la t e more t ransve rse , not

extending beyond sub-gen i ta l p l a t e ; median notch shal low (0.15 mm d e e p ) .

Sub-genital p la t e fused with sternum 7 (as in a l l female b laber id

cockroaches ) , i t s an t e r i o r margin s l i g h t l y convex, pos t e r i o r margin

semic ircular with sinuate o u t l i n e . Geni ta l ia not s tud i ed .

Male nymph (subimago ) . Head broad, d is tance near ly ha l f head width,

i n t e r o c e l l a r d i s tance 0.35X head width; f r on t o f head brown with

scattered dark punctat ions , mouthparts l i g h t e r c o l o r e d , max i l l a r y palpus

as in a d u l t . Antenna brown; pronotum convex, semic i rcular in o u t l i n e ,

pos te r i o r margin t r ansve r s e , l a t e r o - p o s t e r i o r angles broadly rounded and

extending p o s t e r i o r l y ; meso- and metanota exposed ; t ransverse wing pads

seen as broad ly rounded l a t e r o - p o s t e r i o r ang les ; c o l o r o f e n t i r e no tun

l i g h t g r a y , h e a v i l y marked with b lack punctations and dark brown spo t s ,

spots concentrated c e n t r a l l y along pos t e r i o r margins o f t e r g a .

Abdominal terga bear acute spines at l a t e r o - p o s t e r i o r angles and ra ised

c i c a t r i c e s as descr ibed for a d u l t ; each c i c a t r i x marked by dark brown

spot; o ther spots on t e rga apparent ly formed by c l u s t e r s o f scat tered

dark punctat ions . Overa l l c o l o ra t i on shows " s a l t and pepper" e f f e c t

c h a r a c t e r i s t i c o f Epilampra. Supra-anal p late semic ircular with broad ly

rounded l a t e r o - p o s t e r i o r margins r e f l e xed and median notch at pos t e r i o r

end; c o l o r a t i o n gray with numerous punctat ions ; t an , b lack-t ipped c e r c i

22

s t ou t , weakly segmented. Abdominal sterna l i g h t brown with dark

puncta t ions ; sub-gen i ta l p l a t e with r i g h t s t y l e p resent , l e f t absent

( e a r l i e r i n s t a r s have symmetrical paired s t y l e s ) .

Types. Holotype ma le , a l l o t y p e female, 6 male and 3 female

paratypes and 2 nymphs a l l from Costa Rica, Heredia Prov ince , Finca La

Selva near Puerto V i e j o , c o l l e c t e d by me during 1979 and 1980; o ther

male and female paratypes from same l o c a l i t y c o l l e c t e d by F.W. Fisk in

March 1974.

Remarks. Epilampra i n v u l u c r i s may be separated from other spec i es

in the Carinulata Group by means o f the key. Based on ex t e rna l

morphology alone i t i s d i f f i c u l t to separate from b e l l i , but the

male g e n i t a l i a are d i s t i n c t . A l s o , based on present knowledge, the

spec ies are a l l o p a t r i c ; i n v o l u c r i s i s found in the Caribbean lowlands o f

nor th -cent ra l Costa Rica wh i l e b e l l i occurs in the Pac i f i c highlands in

southern Costa Rica near the Panama bo rde r . Epilampra i n v o l u c r i s i s

commonly found in both primary and secondary ( o l d e r than 20 yea rs )

f o r e s t s . The males r e s t in l e a f - l i t t e r by day but c l imb onto v e g e t a t i on

at dusk, r a r e l y c l imbing higher than 50 cm above the ground ( see Chapter

3 ) . Females and nymphs occur in the l e a f - l i t t e r though o c c a s i o n a l l y

l a t e ins ta r nymphs and females climb as w e l l . The courtsh ip sequence

i s somewhat s imi la r to that o f Gromphadorhina portentosa (Schaum)

(Barth, 1968) . Fo l lowing contact with a female the male arches h i s

abdomen down and then up in a sweeping motion un t i l he contacts the

f ema le ' s g e n i t a l i a . The more common sequence noted in B l a t t a r i a ,

namely, mounting o f the male by the f emale , does not occur in t h i s

23

spe c i e s . Copulation takes p lace in the usual opposed pos i t i on and l a s t s

20 to 30 minutes. As in other b laber id cockroaches, the oothecae are

not deposited e x t e r n a l l y but are held in the g e n i t a l pouch unt i l the

young are hatched. Dissect ion o f six oothecae d i sc l osed 50 ± 2.53 (mean

±standard d e v i a t i o n ) developing embryos in each.

The name i n v o l u c r i s r e f e r s to the f l i g h t l e s s condi t ion which t h i s

species shares with most members o f the Carinulata Group.

Epilampra b e l l i Fisk and Schal, NEW SPECIES

F i g s . 2-1D, 2-1E, 2-1F

Male ho lo t ype . Measurements in Table 2-2. Head broad and f l a t ;

in terocu lar d i s tance jus t over ha l f head width, i n t e r o c e l l a r d i s tance

one th i rd head width; dark reddish brown co lo r o f body and head extends

to c l ypeus ; c lypeus and mouthparts bu f f ; expanded d i s t a l segment o f

clypeus v e l v e t y g r ay ; antenna brown. Pronotum and tegmina as in

i n v o l u c r i s ; both spec i es show suffused spr inkl ing of darker spots around

margins o f pronotum and tegmina comparable to black punctations o f other

Epilampra. La t e ro -pos t e r i o r angles o f abdominal terga 2-4 about 90

degrees , o f t e r ga 5 and 6 acute , s p i n e l i k e , o f tergun 7 rounded. Terga

smooth except for c i c a t r i c e s along d i s t a l margins; t e r g a l

s p e c i a l i z a t i o n s absent . Supra-anal p la te extends beyond sub-geni ta l

p l a t e , broad ly rounded p o s t e r i o r l y with very shal low notch; exposed

port ion o f p la t e most ly transparent with scattered s e t ae ; cercus l i g h t

brown, ap ica l segment s l ende r , b l ack - t i pped . Abdominal sterna and

sub-genital p la te as in invo l ucr i s ( r i g h t s t y l e present , l e f t absent) .

24

Gen i t a l i a ( F i g s . 2-1D,E f F) s im i l a r to those o f i n v o l u c r i s except as

f o l l o w s : R2 l a c k s any s p l i t on i t s outer c i r cumfe rence , L1 more

s c l e r o t i z e d , L2d wi th f r e e s c l e r o t i z e d por t i on shaped l i k e hammerhead,

proximal ex t ens i on t r u n c a t e , a p i c a l ex tens ion b l u n t - t i p p e d ;

a d d i t i o n a l l y , a s c l e r o t i z e d por t i on extends i n t o membranous prepuce ;

prepuce n e a r l y t r a n s p a r e n t , l a c k i n g m i c r o t r i c h i a e . Legs d i f f e r from

those o f i n v o l u c r i s o n l y in 3 ( ra ther than 4 ) l a r g e sp ines on

v e n t r o - p o s t e r i o r margin o f hind-femur and smal ler t a r s a l a r o l i a .

Female a l l o t y p e . External f e a tu r e s s imi la r to ho lo type except as

no ted : P o s t e r i o r margins o f tegmina b road l y rounded, merging with

l a t e r o - p o s t e r i o r a n g l e s ; abdominal t e rga 3-7 w i th l a t e r o - p o s t e r i o r

angles a c u t e , s p i n e l i k e ; supra-anal p l a t e uniform dark redd ish brown,

p o s t e r i o r margin wi thout median no t ch ; sub - g en i t a l p l a t e w i th

an t e r i o r margin s l i g h t l y convex , p o s t e r i o r margin s e m i c i r c u l a r .

Types. Ho lo type male and a l l o t y p e female from Costa R ica ,

Puntarenas P r o v i n c e , Finca Las Cruces near San V i t o , c o l l e c t e d by W.J.

Be l l January 27. 1980; one male paratype c o l l e c t e d by M. Kosztarab

February 12, 1970 a t same l o c a l i t y ; one ma l e , 3 female paratypes

c o l l e c t e d by F.W. Fisk February 4 -6 , 1974 from same l o c a l i t y .

Remarks. Epilampra b e l l i i s c l o s e s t to i n v o l u c r i s but can be

separated from i t as noted in the key and remarks under invo l u c r i s . Very

l i t t l e i s known o f i t s b i o l o g y except that i t f a vo rs v e r y mo i s t

h a b i t a t s . The s p e c i e s i s named a f t e r Dr. W i l l i am J . Be l l who

c o l l e c t e d the type spec imens .

25

Epilampra un i s t i l a t a Fisk and Schal, NEW SPECIES

F i g s , 2-1G, 2-1H, 2 -1 I t 2-2B

Male ho l o t ype . Measurements in Table 2-3 . Head f l a t ; in te rocu lar

and i n t e r o c e l l a r distances near l y equa l , about a quarter head width ;

vertex t an ; near l y black i n t e r o c e l l a r band present ; face and mouthparts

mostly bu f f ; maxi l lary palpus with f i f t h ( d i s t a l ) segment covered with

gray m i c r o t r i c h i a e , segments 3 and 4 subequal in l e n g t h , shorter than 5;

antenna brown; pronotum exposing ver tex of head and dorsal areas o f

compound e y e s ; pronotum vau l t ed , anter ior and l a t e r a l margins forming a

s e m i c i r c l e ; l a t e r o -pos t e r i o r angles broadly rounded, r i g h t and l e f t

pos t e r i o r margins s t r a i g h t , meeting at 120 degrees ang le ; base co l o r

mottled red brown, interrupted by poor ly def ined pale median l i n e .

Tegmina f u l l y deve loped, extending beyond t i p s o f c e r c i ; d i s c o i d a l

sec to rs (M + Cu ve ins ) o b l i q u e ; wings and tegmina t ransparent , t i n t ed

with reddish brown, but tegmina also with darker brown mo t t l i n g . L ight

brown abdominal terga have l a t e r o - p o s t e r i o r angles broadly rounded ,

c i c a t r i c e s ba re l y v i s i b l e , t e r ga l s p e c i a l i z a t i o n s l a ck ing ; supra-anal

plate semic i r cu la r , rounded pos te r i o r margin with obl ique median

emargination; cercus s lender , near ly 7X longer than wide .

Gen i ta l i a ( F i g s . 2-1G,H,I) cha rac t e r i s t i c for Group; R2 small and

stout with blunt t i p , no subapical inc i s i on or slender setae on sheath;

L1 with a deep open c l e f t ; L2d with f la t tened s c l e r o t i z ed port ion ovate

d i s t a l l y , proximal port ion (ad jacent to L2vm) with deep U-shaped

emarginat ion. Sub-genital p late ( F i g . 2-2B) convex a n t e r i o r l y and

p o s t e r i o r l y , pos te r i o r margin with ample median emarginat ion, s i n g l e

26

s t y l e a r i s i n g from r i g h t edge o f emarg inat ion . Abdominal sterna l i g h t

reddish brown with scat tered darker t i ny spo t s , no spots on l e g s and

ven t ra l thorax ; v e n t r o - a n t e r i o r margin o f f r on t femur with 3 l a r g e

spines separated by row o f w ide ly spaced minute setae from 2 a p i c a l

sp ines ; ' v e n t r o - a n t e r i o r margins o f mid- and hind-femora a l so

v e n t r o - p o s t e r i o r margins o f f r on t and mid-femora a l l with 3 l a r g e sp ines

plus ap i ca l sp ine , v e n t r o - p o s t e r i o r margin o f hind-femora as above but

lacks a p i c a l s p i n e ; in a d d i t i o n , mid- and hind-femora bear g en i cu la r

sp ine . T ib iae f u l l y sp ined ; t a r s i with obvious p u l v i l l i on 4 proximal

tarsomeres ; arolium present ; claws s imple , symmetr ica l .

Female a l l o t y p e . Simi lar to male in externa l form and co lor except

as f o l l o w s : I n t e r o c e l l a r band not so dark ; supra-anal p la t e with l a r g e

pos t e r i o r median emarg inat ion ; c e r c i l e s s s l ende r , about 4X longer than

wide; sub -gen i t a l p l a t e with pos t e r i o r semic i rcu lar margin e n t i r e ;

v e n t r o - a n t e r i o r margin o f f r on t femur with 4 l a r g e spines ( ra ther than

3 ) ; v e n t r o - p o s t e r i o r margin o f hind femur with 4 spines plus gen i cu la r

spine .

Types. I c o l l e c t e d the ho lo type and a l l o t ype in copulo May 4, 1979

in Costa Rica , Heredia Prov ince , Finca La Selva near Puerto V i e j o ; 5

male and 3 female paratypes c o l l e c t e d by me in 1979» same l o c a l i t y ; 3

male paratypes c o l l e c t e d in l i g h t t raps by H. Wolda July 10 and October

13» 1977 in Panama, Chir iqui P rov ince , Fortuna; 5 male paratypes

c o l l e c t e d in l i g h t t raps by H. Wolda February 17 and May 10, 1980 in

Panama, Bocas de l Toro P rov ince , Corr iente Grande, on Rio Changuinola.

27

Remarks. Epilampra u n i s t i l a t a i s the on ly member o f the Carinulata

Group t o have f u l l y d eve l oped , funct ional wings and tegmina. I t i s

placed in the group because o f the s ing l e r i g h t s t y l e ( from which the

name i s d e r i v e d ; Lat in S t i l u s ) and the morphology o f the male g e n i t a l i a

which are most s imi la r to those o f car inulata .

Va r i a t i ons among the paratypes are noted in the i n t e n s i t y o f

c o l o r a t i o n and the sp inat ion o f the l e g s , tha t i s . the v e n t r o - a n t e r i o r

margin o f the f ront femur has 4 (sometimes 3 ) spines separated by a row

of f i n e setae from the 2 (sometime 1) ap ica l sp ines ; the

v e n t r o - p o s t e r i o r margin o f the mid-femur usual ly has 4 plus a d i s t a l

sp ine ; and the hind-femur usua l ly has 4 l a r g e spines but no d i s t a l

spine .

Epilampra u n i s t i l a t a occurs in the lower under s to ry o f lowland

r a i n - f o r e s t s ( s ee Chapter 3 ) . Males are a c t i v e s t a r t i n g around sunset .

They usua l l y climb t o 0.5 t o 1.5 m above the ground. As noted above ,

they have been taken in l i g h t t r a p s . Females are r a r e l y seen and

usual ly occur lower in the v e g e t a t i o n . Courtship was not observed , but

copulat ion i s in the t y p i c a l opposed p o s i t i o n . The ootheca o f one

female contained 3 6 deve lop ing embryos.

Epilampra r o t h i Fisk and Schal . NEW SPECIES

F i g s . 2-1 J , 2-1K, 2-1L, 2-2A. 2-2C

Male ho lotype ( l i g h t f o r m ) . Measurements in Table 2-4. Head f l a t ,

with i n t e r o cu l a r and i n t e r o c e l l a r d i s tances equa l , one fourth as wide as

head; ve r t ex pale cinnamon, i n t e r o cu l a r space suffused with dark brown.

28

darkest ad jacent to inner margins o f eyes and o c e l l a r s p o t s ; c e n t r a l

brown mark j u s t below o c e l l i and separated from in t e r o cu l a r band by pa l e

tan a r e a , the mark connected d o r s o - l a t e r a l l y wi th pair o f coramalike

s p o t s , t h e i r "heads " d i r e c t l y beneath but not touching o c e l l i ; pa i r o f

median brown spots on clypeus be low c en t ra l mark; remainder o f head pa l e

except gray-brown segments 4 and 5 o f m a x i l l a r y pa lpus ; antenna brown.

Vaulted pronoturn cover ing most o f head; ground co lo r o f pronotum and

tegmina cinnamon, d i s c with d i f f u s e pat tern o f darker a r eas ; wide

borders o f pronotum and c o s t a l margins o f tegmina pa le with sca t t e red

darker s p o t s ; tegmina and wings t r ans lucen t . Abdominal terga t a n ,

l a t e r o - p o s t e r i o r angles rounded, no c i c a t r i c e s or t e r g a l

s p e c i a l i z a t i o n s ; supra-anal p l a t e semic i rcu lar wi th median emarginat ion

not e v i d e n t in holotype (but present in some p a r a t y p e s ) ; cercus s l e n d e r ,

about 5X l onge r than wide; g e n i t a l i a as in F i g s . 2 -1J ,K ,L ; R2 with

obvious subapica l inc i s i on and row o f s lender sp ines proximal to b a s e ;

L1 with short open c l e f t , s e t a l brush lack ing but a few wide ly s ca t t e r ed

m i c r o t r i c h i a e at that s i t e ; L2d shaped l i k e mi t ten with thumb extended

a t near r i g h t a n g l e ; prepuce c l e a r l y de f ined by i t s s c a l e l i k e c o v e r i n g .

Legs and v e n t r a l surfaces o f thorax and abdomen tan with a few darker

spo t s , abdominal sterna i n c r e a s i n g l y darker towards p o s t e r i o r ; r edd i sh

brown sub-gen i t a l p la te ( F i g . 2-2C) convex a n t e r i o r l y , t r i g o n a l

p o s t e r i o r l y with near l y s t r a i g h t l a t e r o - p o s t e r i o r margins meeting a t

mid l ine as a blunted r i gh t a n g l e , s imple s t y l e l o ca t ed at center o f each

l a t e r o - p o s t e r i o r marg in ; r i g h t s t y l e somewhat l a r g e r . Ven t ro -an t e r i o r

margin o f f r o n t femur with 5 l a r g e sp ines separated by row o f c l o s e - s e t ,

short se tae from 2 ap i ca l sp ines ; v e n t r o - a n t e r i o r margins o f mid- and

29

hind femora with 3 l a r g e spines plus ap ica l sp ine , o f mid femur with 4

spines plus ap i ca l s p i n e , o f hind femur with 4 spines o n l y ; t i b i a e f u l l y

spined; t a r s i with p u l v i l l i on 4.proximal tarsomeres and arolium on

f i f t h tarsomere between s imple , symmetrical c l aws .

Male paratype (dark f o r m ) . D i f f e r s from holotype in co l o r as

f o l l ows ( F i g . 2 - 2A ) : Ground co l o r of whole body b u f f , contrast ing with

numerous dark brown markings; ver tex o f head pale with dark s t r i p e s just

dorsal and v e n t r a l to i t , the 2 v en t ra l s t r i p e s f i l l i n g most o f the

inter ocular plus i n t e r o c e l l a r space ( s t r i p e s fused on the midl ine in

some pa ra t ypes ) ; below s t r i p e s , but separate , i s c en t ra l dark mark with

i t s d o r s o - l a t e r a l commalike e x t ens i ons ; t h i s mark fused with c lypea l

spots noted in h o l o t y p e , r e su l t i ng in ve ry dark c en t r a l mark with well

defined margins which, along with small l a t e r a l spots and black

mandibles, comprises c h a r a c t e r i s t i c f a c i a l pa t t e rn ; max i l l a r y palpus

with l i g h t and dark bands on a l l segments. Dark d isc o f pronotum

contrasts sharply with pa le but spotted borders ; ve ry dark marks

i r r egu la r (but c ons i s t en t ) in shape; obvious c en t ra l pale area within

disc enc los ing 2 p a i r s o f small b lack d o t s ; tegmina with numerous dark

brown spo ts , some fused into mott led dark areas e s p e c i a l l y along rad ia l

v e in ; venter o f thorax and abdomen plus l e g s marked with numerous near ly

black spo t s ; some l a r g e r marks on coxae and femora and dark bands on

t i b i a e and t a r s i . ; sub-gen i ta l p l a t e and 2 adjacent sterna reddish brown

except fo r narrow pa l e l a t e r o - p o s t e r i o r bo rde r s .

Female a l l o t y p e ( l i g h t f o rm ) . Similar to male ho lotype except as

f o l l o w s : General c o l o r a t i o n more i n t e n s e , dark markings on face as in

30

dark form except the 2 c l ypea l spots not fused with cen t ra l face mark;

d isc o f pronotum and most o f tegmina pale with numerous dark s p o t s ;

abdominal terga shading to dark reddish brown towards supra-anal p l a t e ;

p la te dark with narrow pa le borders and short median s t r i p e extending

a n t e r i o r l y from p o s t e r i o r margin about a quarter l ength o f p l a t e ;

pos te r i o r margin with ob l i que median emarginat ion; l e g s and venter o f

thorax and abdomen co lored as in dark form males ; sub-geni ta l p l a t e

sanie i r e ular in o u t l i n e .

Female para types . Other Costa Rican females l e s s i n t e n s i v e l y

colored than a l l o t y p e , correspond more to cinnamon colored l i g h t - f o r m

males, whi le Panamanian females correspond to dark form males ; that i s ,

they have 2 c l ypea l spots fused with cent ra l f a c i a l mark, dark pronota l

d isc with cent ra l pa le area and no cinnamon co lo r on dorsum.

Types. Holotype and a l l o t y p e taken in copulo by me February 23»

1980, Costa Rica , Heredia P rov ince , Finca La Selva near Puerto V i e j o ; 6

male and 3 female paratypes a l so c o l l e c t e d by me in 1979 and 1980, same

l o c a t i o n ; 2 female paratypes c o l l e c t e d by M. Kosztarab and A. Young in

l i g h t t r a p , January 10, 1970, same l o c a t i o n ; 2 female and 2 male

paratypes taken by H. Wolda in l i g h t t r a p s , May 1978, May and June

1979» Panama, Chir iqui P rov ince , Fortuna; 24 male and female paratypes

taken by H. Wolda in l i g h t t rap between January 13 and May 10, 1980,

Panama, Bocas de l Toro Prov ince , Corr iente Grande on Rio Changuinola.

Remarks. Epilampra r o t h i appears to represent the u n . sp . D" o f

Dr. Louis M. Roth (1970b) for whom I have named the s p e c i e s . As

31

ACKNOWLEDGEMENTS

I thank G.W. Byers and C D . Michener for c r i t i c a l l y reading the

manuscript. W.J. Be l l and H. Wolda supplied va luab le specimens. L.M.

Roth g r a c i o u s l y permitted me to use an i l l u s t r a t i o n ( F i g . 2-1J) from

pointed out by Roth i t i s c l o s e s t to but d i s t i n c t from Epilampra az teca

Saussure and f a l l s in Group C o f the Burmeisteri Group o f Epilampra. I t

e xh ib i t s cons iderab le range in c o l o r a t i o n . The dark form ( from Panama)

with s t r i k i ng dark markings aga inst a pale background ( F i g . 2-2A) most

c l o s e l y resmbles az teca and has been mistakenly i d e n t i f i e d as azteca in

the past (Roth, 1970b), whi le the l i g h t form (from Costa Rica and the

adjacent Chir iqui Province o f Panama) with suffused chestnut brown

markings on a cinnamon brown background appears qu i t e d i f f e r e n t . Both

populat ions agree in ex te rna l morphology and male g e n i t a l i a , and I ara

t r ea t ing them as one s p e c i e s . As noted in the desc r i p t i ons some

ind i v idua l s show co l o r pa t t e rns between the dark and l i g h t extremes.

Epilampra r o th i i s probably the most common spec i es o f i t s s i z e in

the lower understory o f the Costa Rican lowland r a i n - f o r e s t , but i t i s

apparent ly more r e s t r i c t e d in i t s Panamanian d i s t r i b u t i o n . Males are

common on l eaves s t a r t i n g about sunset usual ly 0.5 t o 1.5 m above ground

(see Chapter 3 ) . Females are r e a l t i v e l y scarce and occur lower in the

v e g e t a t i o n , wh i l e nymphs are common in the l e a f - l i t t e r . Copulation i s

in the opposed p o s i t i o n . Courtship was not observed. I c o l l e c t e d 3

males o f t h i s spec i es in north c en t ra l Nicaragua along the Rio Bocay.

32

h i s 1970b pape r . The hab i tus drawing ( F i g . 2-2A) was done by L.

T r i p l eh o rn . Supported in pa r t by NSF grant BUS 77-24898 to W.J. B e l l .

This c h a p t e r , w i th s l i g h t m o d i f i c a t i o n s , was publ ished with Frank W.

Fisk in the P roceed ings o f the • Entomological S o c i e t y o f Washington

83:694-706 ( 1 9 8 1 ) - Copyr ight 1981 by the Entomologica l Soc i e t y o f

Washington.

Table 2 - 1 . Measurements o f a d u l t Epilampra i n v o l u c r i s in mm.

Ho lo type

male

Tota l l e n g t h 1 9 . 0

Pronotum, l e n g t h 5.3

Pronotum, width 7.5

Tegmen , l e n g t h 6 . 3

Tegmina, width 9 . 0

Abdomen, l e n g t h 1 1 . 9

H i n d - t i b i a , l e n g t h 7.2

6 Paratype A l l o t y p e 3 Paratype

males female f emales

(Range) (Range)

16 .6 -22 .6 25.6 25 .4 -28 .2

5 .0 -5 .5 7 .0 5 .5 -6 .9

7 .7 -8 .5 10.2 9 .1 -10 .2

5 .9 -6 .9 7 .9 5 . 9 - 9 . 0

8 .7 -10 .2 12.2 10 .9-12.4

11 .8 -14 .0 14.5 12 .4-14 .6

6 .6-8 .5 9.2 8 .3 -9 .8

Table 2 -2 . Measurements o f Epilampra b e l l i in ram.

male males female females

(Range) (Range)

Total l e n g t h * 18.6-19 .0 22.2 22.4-26.5

Pronotum, l eng th 5.2 5 .1 -5 .8 6.0 6 .3 -8 .0

Pronotum, width 7.2 7 .1 -7 .3 8.4 9 .1-10 .0

Tegmen, l eng th 6 .3 5 .9 -6 .1 7.7 7-9-9 .8

Tegmina , width 8.8 8 .9-9 .1 10.9 10.9-12.4

Abdomen , l eng th * 9 .5 -10 .1 15.8 14.5-17.1

H i n d - t i b i a , l eng th 6.5 6 .6 -6 .8 8.2 7 .5-9-5

* T ip o f abdomen removed fo r d i s s e c t i o n o f g e n i t a l i a .

Holotype 2 Paratype A l l o t y p e 3 Paratype

Table 2-3. Measurements o f Epilampra un i s t i l a t a in mm.

Holotype

male

Total l ength 20.2

Pronotum, length 4.0

Pronotum, width 4.9

Tegmen, l eng th 16.7

Tegmina, width 9.1

Abdomen, l ength 9.3

H ind - t i b i a , l ength 6.7

8 Paratype A l l o type 3 Paratype

males female females

(Range) (Range)

20.8-22.4 23.0 24.4-24.8

4 .0-4 .3 4.4 4.8-5.0

5.1-5.6 6.6 6.7-7.2

17.7-19.7 19.4 20.0-20.8

9.1-10.5 10.5 9-3-10.3

9.1-10.4 10.7 — 6.5-6.8 7.3 7.4-7.7

Table 2-4. Measurements o f Epilampra r o t h i in mm.

(Costa R i ca ) male males female females

(Range) (Range)

Tota l l eng th 20 .0 19.4-20.2 20.8 19.4-22.3

Pronotum, l eng th 4 .2 3 .7 -4 .1 4.3 4 .1 -4 .7

Pronotum, width 5.1 4 .7 -5 .7 5.7 5.4-6.6

Tegmen , l e n g t h 16.8 16 .6-17 .3 17.0 16.0-19.4

Tegmina, w idth 8.2 7 .5 -9 .4 9.0 8 .4-9 .9

Abdomen, l e n g t h 10.8 10.4-11.0 11.1 11.5-13.8

H i n d - t i b i a , l e n g t h 6.3 5 .4-6 .5 6.0 6 .0-6.6

Dark Form

(Panama)

Total l eng th

Pronotum, l eng th

Pronotum, width

Tegmen , l e n g t h

Tegmina, w idth

Abdomen, l e n g t h

H i n d - t i b i a , l e n g t h

24 Paratype

males

(Range)

18 .2-20.6

3 . 9 -4 . 4

4 .7 -5 .0

16.0-18.3

7 .7 -9 .3

10.3-11•1

5 .1 -6 .4

3 Paratype

females

(Range)

20 .7-21 .3

3 -7-4 .7

5 .0-5 .9

16.1-17.9

9 .1-10.0

9 .9 -12 .4

5 .2-6 .6

L ight Form Holotype 8 Paratype A l l o t y p e 5 Paratype

37

ure 2 - 1 . Male g e n i t a l i a o f Epilampra s p e c i e s . A.B.C, E.

i n vo l u c r i s . D,E.F, JL_ b e l l i . G .H . I . u n i s t i l a t a . J f K, L, E.

r o t h i . A .D.G.J . Ventro-medial s c l e r i t e o f l e f t phallomere (L2vm) f

dorsa l s c l e r i t e o f L2 (L2d) f prepuce ( P ) . B,E,H,K. Hooked s c l e r i t e

o f r i g h t phal lomere (R2) , subapica l i n c i s i o n ( S I ) . C .F . I . L . F i r s t

s c l e r i t e o f l e f t phal lomere ( L 1 ) » c l e f t (C) . Scale bars = 0.5 mm.

F i g . J from Roth (1970b. f i g . 2 8 1 ) .

39

Figure 2-2. k. Male Epilampra r o t h i , habitus o f dark form; sca l e bar =

6.2 mm. B f C t Ventral aspec t o f d i s t a l part o f abdomen. B, JL

u n i s t i l a t a . C, E. r o t h i . Sca le bars for B and C = 2.0 mm.

41

CHAPTER 3

V e r t i c a l Community Structure and Resource U t i l i z a t i o n of Some

Costa Rican Rain-Forest Cockroaches

The pat terns o f v e r t i c a l habi tat use among ten spec ies o f

cockroaches are examined. Three assemblages o f cockroaches are

separated on the bas i s o f over laps and breadths o f v e r t i c a l

d i s t r i b u t i o n s . Three apterous or brachypterous spec ies occur near the

ground and comprise one assemblage. Higher perchers separate into those

which migrate into the l e a f - l i t t e r on a d i e l b a s i s , and those which hide

in above-ground re fug ia during the day. Trophic and behav iora l

c o r r e l a t i o n s with perch height are desc r ibed .

42

INTRODUCTION

Close ly r e l a t ed sympatric spec i es d i f f e r in t h e i r u t i l i z a t i o n o f

environmental r e sou r c e s . Numerous s tudies r epor t d i r e c t or i n d i r e c t

evidence o f v e r t i c a l s t r a t i f i c a t i o n o f animals. The f o l l ow ing i s merely

a sampling from the vast natural h i s t o r y l i t e r a t u r e . Adams (1941) noted

that "some animals are commonly found on the ground, o thers on the herbs

and s t i l l other spec i e s a t d i f f e r e n t l e v e l s in the shrubs and t r e e s . "

Zooplankton migrate upward at sunset to feed on phytoplankton, and down

at sunr i s e , probably to avoid v i sua l predators in the epi l imnion ( Za r e t

and Suf fern, 1976) . Narver (1970) and Eggers (1978) showed that some

f i l t e r - f e e d i n g f i sh f o l l o w v e r t i c a l l y migrat ing zooplankton in a d i e l

pat tern . Beginning with the work of Dunlavy (1935) and Colquhoun and

Morley ( 1943)» b i r d s formed a model for the study o f v e r t i c a l niche

separation (see Mac Arthur, 1965; Cody, 1974; Lack, 197D. Schoener

(1974) and Pianka (1973) reviewed the per t inent l i t e r a t u r e in the study

o f l i z a r d community s t ruc tu r e . The increased i n t e r e s t in s t r a t i f i c a t i o n

o f f o r e s t s in to v e r t i c a l l a y e r s stimulated the s tudies o f Napier (1966)

and Charles-Dominique (1977) on primate d i s t r i b u t i o n s . Enders (1974)

found that two c l o s e l y r e l a t ed spider spec ies coex is ted as adul ts

because o f high m o r t a l i t y among the v e r t i c a l l y s t r a t i f i e d immatures.

Di f f e rences in the v e r t i c a l d i s t r i b u t i o n s o f l i f e stages and seasonal

va r i a t i ons have been documented in s o i l mites by using core samples

( e . g . , M i t c h e l l , 1978) , and in sp iders (Barth and Sey far th , 1979).

The v e r t i c a l d i s t r i b u t i o n o f insec ts has rece ived l i t t l e a t t e n t i o n .

Howden and Nea l i s ( 1978) reported on v e r t i c a l separat ion o f seven

43

spec ies o f b e e t l e s ; they suggested that d i f f e r e n t sized be e t l e s perch a t

d i f f e r e n t he ights because they forage on d i f f e r e n t sized food. Haddow

(1966 ) , Corbet (1961) and o the r s , looked at b i t i n g a c t i v i t y o f

mosquitoes as a funct ion o f v e r t i c a l d i s t r i b u t i o n , among other f a c t o r s .

Trapping pest spec ies in f o r e s t s and ag r i cu l tu ra l crops ind ica te that

they occur in s p e c i f i c r e g i ons along the v e r t i c a l p r o f i l e . For example,

male gypsy moths tend to f l y near the ground at low population d e n s i t i e s

(Richerson e t a l . , 1976) . Late instar l a rvae and adult gypsy moths have

d i e l pat terns o f v e r t i c a l movement in temperate woodlands (Leonard ,

1970).

Hawke and Far ley (1973) and Edney e t a l . (1974) inves t i ga t ed

i n t r a s p e c i f i c niche separat ion o f the cockroach Arenivaga (Po lyphagidae )

in dese r t sand dunes. Gautier (1974a found ontogenet ic and sexual

d i f f e r e n c e s in the v e r t i c a l d i s t r i bu t i on o f Blaberus átropos and B.

co losseus (B laber idae ) in caves in Tr in idad. Gautier (1980) and

Deleporte (1976) noted s imi la r pat terns for the caverniculous spec i e s

Gyna maculipennis (B l abe r i dae ) and Per i plane ta americana ( B l a t t i d a e ) ,

r e s p e c t i v e l y . For temperate spec i e s , Dre i s i g (197D showed tha t

Ectobius ( B l a t t e l l i d a e ) adul ts migrate upward in the vege ta t i on during

the a c t i v e phase o f the c i r cad ian c y c l e . He proposed that phys i o l o g i c a l

l i m i t a t i o n s r e su l t in d i f f e r e n t i a l a c t i v i t y and d i s t r i b u t i o n pat terns in

adults and nymphs. Gorton (1980) inves t i ga ted in te r and i n t r a s p e c i f i c

v e r t i c a l segregat ion o f cockroaches in northeastern Kansas. He

at t r ibuted th i s to , f i n t e r sexua l , i n t e r s p e c i f i c , and probably

i n t e r - l i f e s t a g e c ompe t i t i on , " but the evidence which he reported to

support th i s thes i s was ra ther meager.

44

Schal (1982 [Chapter 4 ] ) reported that cockroaches in the understory

o f a t r o p i c a l f o r e s t s t r a t i f y in ter and i n t r a s p e c i f i c a l l y . The aim of

the present study was to attempt to explain coex is tence o f severa l

syntopic s p e c i e s . U t i l i z i n g behaviora l observa t i ons , stomach ana lyses ,

micro-environmental measurements, d i s t r i bu t i ona l data , and temporal

a c t i v i t y pa t t e rns , the o v e r a l l ob j ec t i v e was to document the v e r t i c a l

structure o f the cockroach community in the lowest 2 m of a Costa Rican

fo res t and to examine temporal , s p a t i a l , and trophic d i f f e r ence s among

severa l s p e c i e s .

The fo l l ow ing s p e c i f i c questions are cons idered: 1) How are spec ies

and c l asses o f i nd i v i dua l s within spec ies d i s t r ibuted v e r t i c a l l y ? 2)

What f a c t o r s cont r ibute to v a r i a t i o n s in v e r t i c a l d i s t r i bu t i ons ? 3)

Are there morphological or t rophic c o r r e l a t e s with the v e r t i c a l ranges

o f spece ies ? 4) How important i s time in separating syntopic spec ies ?

5) What r e l a t i o n s h i p s can be ca lcu lated between the average height o f a

spec ies and i t s v e r t i c a l range ?

MATERIALS AND METHODS

This study was conducted during three per iods (March to July, 1 9 7 9 .

February to May, 1980, and March to June, 1981) at Finca La Se lva , an

Organization for Trop ica l Studies f i e l d s ta t ion in the Caribbean

o

lowlands o f Costa Rica at a l a t i t u d e o f 10 28 ! N. Holdridge e t a l .

(197D descr ibe the f i e l d s i t e in g rea t d e t a i l with re ference to i t s

h i s t o r y , a b i o t i c f a c t o r s , v ege ta t i ona l composit ion, and so i l t ype s .

I u t i l i z e d two study p l o t s in a successional abandoned p l an ta t i on .

45

2 A l a r g e p lo t (400 m ) was used in a mark-recapture study to examine

2

ind i v idua l v a r i a t i o n s in perch he i gh t . A smaller (100 m ) area was used

to examine the e f f e c t o f d i f f e r e n t v e r t i c a l .vegetat ion p r o f i l e s on

abundance and v e r t i c a l d i s t r i b u t i o n s o f cockroaches.

In n i g h t l y sess ions o f a f i v e month capture-mark-recapture program

in 1979 adults o f ten spec ies were c o l l e c t e d by hand and the s i t e o f

capture was marked . I recorded on magnetic tape which was l a t e r

t ranscr ibed (1 ) the spec i es i d e n t i f i c a t i o n , (2) sex , (3) he ight above

the ground, ( 4 ) t ime o f cap ture , and ( 5 ) behavioral no tes . N i gh t l y

weather patterns were a lso r eco rded .

Marking was done in the l abora to ry without anesthes ia . The pronotum

was scraped with an insec t pin and a drop o f Eastman 910 adhes ive , a do t

o f co lored T e s t o r T s enamel paint and a second coat ing of g lue were

placed success i v e l y at predesignated pos i t i ons on the pronotum, which

along with a co lor code corresponded to a number. The insec ts were

returned to the i r capture s i t e s on the same n i gh t . In subsequent n i gh ts

s ight ing of marked i nd i v i dua l s was recorded; marked cockroaches were not

captured .

The ana lys i s o f v e r t i c a l d i s t r i b u t i o n s and temporal a c t i v i t y

pat terns included data c o l l e c t e d in the l a r ge p lo t and in adjacent

reg ions o f s imi lar v e r t i c a l s t ruc tu re . Thus, unmarked cockroaches seen

outs ide o f the mark-recapture program and not captured were inc luded .

Temporal and r e l a t i v e abundance ca l cu l a t i ons were made on the bas i s o f

t h i s "conspicuousness" r e c o rd . Dre i s i g (1971 ) , Gorton ( 1980 ) . and

others used th i s procedure in the i r s tud i e s . The number of i nd i v i dua l s

o f a g iven ca tegory ( s p e c i e s , sex , a g e - c l a s s ) which were seen was

46

div ided by the cummulative time spent searching (observat ion t ime) to

ca l cu l a t e " r e l a t i v e a c t i v i t y " va lues . I d iv ided the nocturnal a c t i v i t y

period o f cockroaches into hourly i n t e r va l s for most common spec i e s ; a

two hour a c t i v i t y index was computed for the l e s s abundant spec i e s .

Niche, breadth and ove r lap are measures o f e co l og i ca l s p e c i a l i z a t i o n

and the degree to ^which sympatric organisms share resource i n t e r v a l s .

Here, resource i n t e r v a l s are def ined as reg ions along the v e r t i c a l niche

ax is and as hourly i n t e r v a l s during the n i gh t . As a measure o f v e r t i c a l

o v e r l a p , I u t i l i z e d Schoener 's (1968) index o f e co l og i ca l s i m i l a r i t y ,

0 = 1 - H J ^ IPy - P J J J C I )

where p.y and p ^ . are the proport ions o f ind iv idua ls o f spec ies j and

spec ies k which are assoc iated with resource in t e r va l i (see Abrams,

1980; Linton e t a l . , 1981 f for c r i t i c a l discussions o f niche over lap

measures) .

Niche breadth along the v e r t i c a l ax is was calculated as

B = 1 / S p? ( 2 ) 1=1 1

and as

B = exp ( - T P ± l o g p 1 ) ( 3 )

Because a high p o s i t i v e c o r r e l a t i o n was calculated between these two

niche breadth measures ( r=0.995» P<0.0001), only the former was used in

c o r r e l a t i on analyses .

Diel locomotory a c t i v i t y patterns were inves t iga ted outdoor in a

screened insec tary . I d i v ided a l l the surfaces of 30 x 15 x 15 cm cages

in to 7.5 x 7.5 cm squares. The frequency at which 5 ind iv idua ls crossed

47

these l i n e s was a r e l a t i v e measure o f a c t i v i t y (see Block and B e l l .

1974). These data were recorded for 3 min at e i the r 0.5 hr or 1 hr

i n t e r v a l s during continuous 24 hr per iods .

To determine whether v i s i o n was involved in perch height s e l e c t i on

the eyes o f 30 f i e l d c o l l e c t ed JL_ invo l ucris males were painted with

India ink and they were caged in an outdoor insec tary . Unaltered males

were maintained under s imi la r condi t ions . In experimental s e r i e s , equal

numbers o f blinded and cont ro l males were allowed to walk out o f g l a s s

v i a l s onto l eaves at 25 cm and at 100 cm above the ground. I recorded

the time spent on the l e a f before locomotion ensued. Prel iminary

observat ions indicated that whereas ear ly in the night (ca 19.00 hr)

perching ind iv idua ls were r e s t l e s s and tended to move about, by ca 22.00

hr they were more apt to remain on the perch for longer periods o f t ime .

There fo re . I started the experiments at 22.00 hr .

The spec ies involved in the study are as f o l l ows :

Epilampra invo luc r i s Fisk and Schal- Blaber idae. This spec ies i s

very common in a l l the f o r e s t types which I examined . Both sexes are

brachypterous• Females are l a rger than males.

Epilampra ro th i Fisk and Schal- Blaber idae. Males o f th i s spec ies

are probably the most conspicuous insect on understory f o l i a g e at n i g h t .

Females are common only at feeding s i t e s . Both sexes are winged.

E. u n i s t i l a t a Fisk and Schal- Blaber idae. Not a common spec i e s .

Females are r a r e l y seen.

Hyporhicnoda r e f l e x a Saussure and Zehtner- B laber idae . Males are

winged; females are ap te rous . Both sexes and nymphs exh ib i t t on i c

immobil ity when disturbed (Scha l , in p repara t i on ) .

48

Nesomylacris sp . near a s t e r i a - B l a t t e l l i d a e . Very s imi lar in

morphology to i n v o l u c r i s (both sexes are brachypterous) but

s i g n i f i c a n t l y sma l l e r . B e h a v i o r a l l y and in egg case morphology i t i s

more s imi la r to Xes tob la t ta c a n t r a l i i . A common l e a f - l i t t e r s p e c i e s .

Xes tob la t ta hamata G i g l i o - T o s - B l a t t e l l i d a e . Although not v e r y

common in the n open ! t f o r e s t , i t i s conspicuous at s p e c i f i c feeding

s i t e s . Both sexes are winged and s u p e r f i c i a l l y resemble the American

cockroach ( Pe r i p l ane ta americana) .

X. c a n t r a l l i Fisk and Gurney- B l a t t e l l i d a e . Very common. Both

sexes are winged but are smal ler than hamata.

Imb l a t t e l l a impar Hebard, Car ib la t ta imitans Hebard , and new

spec ies "G" ( F i s k , 1 9 7 1 ) - B l a t t e l l i d a e . A l l three spec ies are s im i l a r

morpho log i ca l l y and b e h a v i o r a l l y and are found in the same h a b i t a t s .

Other members o f these genera occur at La Selva but are not common. A l l

adults are winged and are s im i l a r in s i z e to the German cockroach

( B l a t t e l l a germánica ) . Both genera are in the subfamily P l ec top te r inae .

49

RESULTS

(1 ) A c t i v i t y Patterns and Perch Types

Adults o f a l l spec ies except impar f I , new sp . " G l f , and C.

imitans r e s t in the l e a f - l i t t e r during the .day. At dusk ( c a . 18.00 h r )

males and females cl imb or f l y onto understory f o l i age . . Before sunrise

( c a . 05.00 hr) they move downward to the l e a f l i t t e r . The he ight to

which they move and the temporal pat terns o f these behaviors vary both

i n t e r - and i n t r a - s p e c i f i c a l l y . Adults and nymphs of Imb la t t e l l a and

Car ib la t ta spend the day in folded dead l eaves and other" above-ground

r e f u g i a .

On l e a v e s , cockroaches feed on e p i p h y l l s , bird droppings, or f a l l e n

mate r ia l s which are trapped as " a e r i a l l i t t e r " . They commonly perch a t

the edge o f l e a v e s ; f l i g h t between l e a v e s i s common in some s p e c i e s .

Females o f severa l spec ies were seen in " c a l l i n g " postures , e v i d en t l y

emit t ing v o l a t i l e sex pheromones to which males are a t t rac ted ( S c h a l ,

1982 [Chapter 4 ] ; Schal e t a l . , in p r epa ra t i on ) .

The type o f perch u t i l i z e d seemed to be a function o f the s i ze o f

the cockroach and i t s pa r t i cu la r escape behav ior . Large spec i e s

(Megalob lat ta b l a b e r o i d e s , Nyctibora noct ivaga ( B l a t t e l l i d a e ) , and

Blaberus colosseus (B labe r idae ) were found mostly on trunks o f t r e e s a t

various h e i g h t s . When d i s tu rbed , they usual ly re t rea ted severa l cm in to

c r e v i c e s or crouched down on the subs t ra te ; they r a r e l y took f l i g h t .

Other spec ies tended to perch on f o l i a g e and commonly f l ew away or

jumped o f f the l e a f into the l e a f - l i t t e r when d i s turbed .

50

( 2 ) I n t e r s p e c i f i c V e r t i c a l S t r a t i f i c a t i o n and Niche Met r i cs

The d i s t r i b u t i o n s o f adu l t s o f a l l s p e c i e s (w i th the except ion o f X.

hamata v s . u n i s t i l a t a , X. c a n t r a l l i v s . r o t h i y and 1^ impar

v s . im i t ans ) are s i g n i f i c a n t l y d i f f e r e n t from each other (P<0.05»

S tudent ' s t - T e s t o f l o g transformed data and Wilcoxon Rank Sum Tes t )

( F i g . 3 - D . These d i s t r i b u t i o n s r epresen t the t o t a l number o f

obse rva t i ons r e g a r d l e s s o f the t ime o f n ight or the c l i m a t i c c o n d i t i o n s .

To j u s t i f y the use o f means as ev idence f o r v e r t i c a l hab i t a t

p a r t i t i o n i n g , the t rue ranges o f spe c i e s must not extend far above the

2.2 m upper l i m i t o f sampling. Food ba i t ed t raps a t ground l e v e l , 0.5

m, 3 m» and 10 m above the ground were deployed to independent ly assess

the v e r t i c a l d i s t r i b u t i o n o f cockroaches . Most i n d i v i d u a l s o f a l l

spec i e s were trapped e i t h e r at ground l e v e l or at 50 cm above the ground

(Table 3 - D . The adu l t catch in the 3 m and 10 m t raps was on ly 8.5% o f

the t o t a l adul t c a t c h . Because sampling commenced at 21.00 hr when

cockroaches were a c t i v e above ground , i t was safe to conclude tha t the

lower 2 m o f the v e g e t a t i o n did indeed r epresen t the true range o f these

s p e c i e s .

Ihe v e r t i c a l d i s t r i b u t i o n r e s u l t s ( F i g . 3-1) i nd i ca t e that the

var iance in the v e r t i c a l range i s r e l a t e d to the mean perching h e i g h t .

To r e f l e c t the p r o b a b i l i t y o f co -occurrence o f spec i e s in a g i v en

resource i n t e r v a l , I app l i ed a a we ight ing f ac to r to each one based on

the v e g e t a t i o n p r o f i l e ( F i g . 3 - 2 ) . That i s , the propor t i on o f

i n d i v i d u a l s u t i l i z i n g each resource i n t e r v a l was cor rec ted on the

assumption that r esource u t i l i z a t i o n i s r e l a t e d to the a v a i l a b i l i t y o f

51

l eaves ( o r with i n d i r e c t v e g e t a t i on a f f e c t s on temperature, humidity ,

r a d i a t i o n , e t c . ) . and that i n d i v i d u a l s o f a spec ies sample randomly from

the a v a i l a b l e r esources . Such weighting of niche measures accounted for

the r e l a t i v e abundance or a v a i l a b i l i t y o f resources (perches ) ( s e e

Schoener, 1974; Hanski, 1978; Hur lber t , 1978). Since in the present

study the v ege ta t i on was most dense c lose to the ground, over lap ind i c e s

between low perchers (E . invo l u c r i s , Nesomylacr is , H. re f l e x a) and

high perchers ( I m b l a t t e l l a and Car ib la t ta ) were most a f f ec ted by these

co r r ec t i on f a c t o r s . For i n t e r s p e c i f i c over lap measures the c o r r e l a t i o n

between niche over lap and t h e corrected over lap measures ( F i g . 3-3) i s

0.985 ( P « 0 . 0 0 1 , Pearson C o r r e l a t i o n ) . As i n t u i t i v e l y expected , spec i e s

over laps are n e g a t i v e l y c o r r e l a t e d with d i f f e r e n c e s between mean spec i es

he ights ( r = -0 .910 , P « 0 . 0 0 1 ; F i g . 3 - 4 ) . A nega t i v e c o r r e l a t i o n a l so

e x i s t s between he ight and t h e l a r g e s t over lap o f each spec ies with i t s

nearest neighbor ( r = - 0 . 6 0 0 , P=0.033 ) .

Three morpho l og i ca l l y d i f f e r e n t assemblages o f cockroaches separate

along the he ight dimension ( F i g s . 3-4, 3 - 5 ) . Adults o f _E_._ i n v o l u c r i s

and Nesomylacr is , and Hk r e f l e x a females are brachypterous and perch

c lose to the ground; on average , l e s s than 5 cm separate means o f

adjacent s p e c i e s . Approximately 20 cm separate means o f hamata and

H. r e f l e x a . X. hamata, E. u n i s t i l a t a , E. r o t h i , and c a n t r a l i i

comprise an intermediate g u i l d ; a l l four spec i es are good f l i e r s and

spend the day in the l e a f - l i t t e r . The mean perch he ights o f 1^ impar ,

C. im i tans , and L n . s p . "G" are within a 12 cm range separated by

40 cm from that o f c a n t r a l l i . These three spec i es are smaller than

the other spec ies and spend the day in above-ground r e f u g i a .

52

V e r t i c a l o v e r l a p v a l u e s were arranged in to symmetrical community

mat r i c es which are summarized as dendrograms o f v e r t i c a l range

s i m i l a r i t y ( s e e Cody, 1974 f o r d i s c u s s i o n ) . As e xpec t ed , three c l u s t e r s

o f s p e c i e s separate on the b a s i s o f v e r t i c a l o v e r l ap ( F i g . 3 - 6 ) . S imi lar

arrangements r e s u l t when consexua ls are c l u s t e r e d .

The th ree assemblages a re a l s o d i s t i n g u i s h a b l e on the b a s i s o f

v e r t i c a l b r ead th . Apterous spec i es occupy a narrow v e r t i c a l r e g i on

c l o s e to the ground , the p l e c t o p t e r i n e spec i e s perch higher and e x h i b i t

g r e a t e r v e r t i c a l b r e a d t h s ; the o the r s are in te rmed ia te between these two

groups . The widths ( b r e a d t h s ) o f s p e c i e s ' v e r t i c a l ranges c o r r e l a t e

d i r e c t l y wi th the s p e c i e s mean perch he i gh t s ( r =0 .968 , P=0.001) ( F i g .

3 - 7 ) .

Because both v e r t i c a l o v e r l a p and breadth are c o r r e l a t e d with perch

he i gh t ( n e g a t i v e l y and p o s i t i v e l y , r e s p e c t i v e l y ) . I examined the

r e l a t i o n s h i p between breadth and o v e r l a p . As v e r t i c a l breadth

i n c r e a s e s . v e r t i c a l o v e r l a p with the c l o s e s t neighbor dec reases

( r = - 0 . 6 3 0 . P=0 .025 ) . That i s , p l e c t o p t e r i n e spec i es ( h i gh v e r t i c a l

b readths ) e x h i b i t l e s s ove r l ap with t h e i r ne ighbors than do

brachypterous s p e c i e s ( l o w v e r t i c a l b readths ) with t h e i r ne i ghbo rs .

Low perching males or females (w i th small v e r t i c a l breadths ) have

ranges tha t o v e r l a p more w i th t h e i r c l o s e s t consexual ne ighbors than do

high perchers ( w i t h g r e a t e r b r e a d t h s ) . This r e l a t i o n s h i p i s

s t a t i s t i c a l l y s i g n i f i c a n t f o r both the male and female popu la t i ons , but

not for each o f the t h r e e consexual assemblages .

53

( 3 ) In t raspec i f i e Ver t ica l S t r a t i f i c a t i o n

I n t r a s p e c i f i c v e r t i c a l separat ion i s as s t a t i s t i c a l l y s i g n i f i c a n t as

i n t e r s p e c i f i c s t r a t i f i c a t i o n , and in severa l c l o s e l y r e la t ed spec ies

( e . g . , I m b l a t t e l l a and C a r i b l a t t a ) , d i f f e r e n c e s in sexual separation are

more s i g n i f i c a n t than spec ies d i f f e r e n c e s ( F i g . 3 - 1 ) . Although t h e i r

v e r t i c a l ranges over lap cons ide rab ly , the d i s t r i b u t i o n s o f c onspec i f i c

females and males are s i g n i f i c a n t l y d i f f e r e n t for a l l species (P<0.05»

Student 's t - T e s t o f log transformed data and Wicoxon Rank Sum T e s t ) .

The d i r e c t i o n o f sexual d i f f e r e n c e s in d i s t r i b u t i o n s are cons i s t en t

for a l l s p e c i e s ; males always perch higher than females . Trapping

r e su l t s (Table 3 -D indicate i n c r eas ing l y male biased sex r a t i o s with

increasing h e i g h t , suggesting that the "male above" pattern may hold for

the e n t i r e v e r t i c a l community p r o f i l e .

The d i f f e r e n c e s in perch he igh ts between females and conspec i f i c

males increase with height above the ground ( r=0 .852 , P=0.0009; F i g .

3 - 8 ) . Here , as in the i n t e r s p e c i f i c pa t t e rns , the same three

assemblages o f cockroaches are r e cogn i z ed . The sexes o f apterous

spec ies which are c lose to the ground are separated by small d i s t a n c e s ;

in the p l e c t op t e r i n e spec ies g r ea t e r d i s tances separate the males from

the f ema les .

S i m i l a r l y , the three groups are recognized in the ana lys i s o f

v e r t i c a l b r ead ths . As for spec i es m e t r i c s , the v e r t i c a l breadths o f

males and females r e l a t e to the i r r e s p e c t i v e mean perching he ights ( F i g .

3 - 7 ) . For the two lower assemblages males have broader v e r t i c a l ranges

than c o n s p e c i f i c females; in the higher perching p l e c t op t e r ine s p e c i e s ,

54

females and males have s imi la r ranges ( F i g . 3 - 7 ) . In the ana l ys i s o f

sexual and s p e c i e s v e r t i c a l b r ead ths , females tend t o br idge the gap

between the assemblages.

For the whole community, no s i g n i f i c a n t r e l a t i o n s h i p e x i s t s between

v e r t i c a l o v e r l aps and the d i s tances between the sexes ( r = -0 .387 »

P=0 .135 ) . However, f o r each assemblage, the two measures are

s i g n i f i c a n t l y n e g a t i v e l y c o r r e l a t e d , as in o ve r l ap between s p e c i e s .

Separat ion o f age c l a s s e s was examined in d e t a i l in four s p e c i e s ;

the pa t t e rn i s s imi la r in the o the rs ( F i g . 3 - 1 ) . Except for the

p l e c t o p t e r i n e spec ies ( I m b l a t t e l l a and C a r i b l a t t a ) , e a r l y i n s t a r s are

found e x c l u s i v e l y in the l e a f - l i t t e r where pa r tu r i t i on occurs or

oothecae are d e p o s i t e d . Older nymphs perch a t higher l e v e l s in the

v e g e t a t i o n . The d i s t r i b u t i o n s o f l a s t ins tar nymphs are c l o s e s t to

those o f adu l t s o f the same sex. For example, most l a r g e nymphs o f E.

r o th i are f ema les ; instead o f ranging higher than smaller nymphs they

perch c l o s e r to the ground, as do adult f ema les .

A l l i n s t a r s of I m b l a t t e l l a and Car i b l a t t a ove r lap in ranges with

each o ther as wel l as with the adu l t s . I t i s not known whether sexual

separat ion o f the nymphs occurs in these s p e c i e s .

( 4 ) Die l A c t i v i t y

H. r e f l e x a males exh ib i t ed a unique a c t i v i t y pat tern ( F i g . 3 - 9 ) .

They were found on f o l i a g e within minutes a f t e r sunset ( c a . 18.00 h r )

and were v e r y common u n t i l c a . 20.00-21.00 hr , at which time t h e i r

above-ground a c t i v i t y dropped abrupt ly and remained low for the r e s t o f

the n i g h t . Laboratory data ( F i g . 3-9) suggest that a c t i v i t y on f o l i a g e

55

of

may be fo l lowed by other k i n d s A a c t i v i t y . After the males moved into the

l e a f - l i t t e r at ca . 21.00 hr they probably remained a c t i v e ( p o s s i b l l y

for the r e s t o f the n i g h t ) as ind ica ted by the locomotory measure in the

l a b o r a t o r y . This suggest ion was a l so corroborated by the trapping

r e s u l t s ; males were trapped in the l e a f - l i t t e r l a t e in the n i g h t .

E. i n v o l u c r i s males moved upward onto f o l i a g e e a r l y but remained

a c t i v e a l l n i g h t . Nesomylacris sp . adul ts occurred in the <40 cm zone

with E^ i n vo l ucr i s and r e f l e x a , but they i n i t i a t e d a c t i v i t y l a t e r

at n ight and were l e s s a c t i v e a f t e r 01.00 h r .

Higher up, X_i can t r a l i i f o l l owed a pattern s imi lar to E.

i n v o l u c r i s . The a c t i v i t y o f hamata adults was bimodal ly d i s t r i b u t e d ;

both males and females were conspicuous between 19.00 and 20.00 hrs and

between 01.00 and 04.00 h r s .

For most s p e c i e s , l abo ra t o r y and f i e l d data are in general agreement

( F i g . 3 - 9 ) . However, the l abo ra t o r y measures accentuate the " o n - o f f "

nature o f locomotory a c t i v i t y . Most spec ies have bimodal a c t i v i t y

patterns with the " on " peak probably corresponding to the locomotion

which i n i t i a t e perch ing , and the " o f f " peak corresponding to the return

back to r e s t i n g s i t e s .

Species with high s p a t i a l over laps may reduce competi t ion between

them by over lapping l i t t l e in t ime . Temporal s h i f t s in a c t i v i t y are

most obvious in the d i u r n a l l y a c t i v e Euphyllodromia angustata. I did not

d e t a i l the v e r t i c a l hab i ta t use in t h i s spec i e s , but both l abora to ry and

f i e l d data ind i ca t e that JL angustata adul ts r oos t on the underside o f

l eaves a t night and are a c t i v e during the d a y - l i g h t hours ( F i g . 3 - 9 ) .

Behav i o ra l l y , they are s imi la r to the p l e c t op t e r ine s p e c i e s .

56

With few e x c e p t i o n s , temporal o v e r l a p among spec ies was l a r g e . For

males o f nine spec i es for which s u f f i c i e n t a c t i v i t y data were a v a i l a b l e ,

a p o s i t i v e c o r r e l a t i o n e x i s t ed between spa t i a l and temporal overlap with

the neares t ne ighbors ( r=0 .857t P=0 .007 ) . A p o s i t i v e r e l a t i onsh ip

between these measures p e r s i s t e d s when a l l v e r t i c a l and temporal

ove r l aps among a l l males in the community were analyzed ( r=0 .169,

P=0 .009 ) .

( 5 ) Hab i ta t Complexity and Height P re f e rence

The average pre fe rence o f i n d i v i d u a l s for s p e c i f i c resources i s

r e f l e c t e d in the i r r e l a t i v e d i s t r i b u t i o n among resource i n t e r va l s when

a l l resources are e q u a l l y abundant. The analyses o f perch d i s t r i bu t i ons

o f spec i e s and sexes were conducted in a f o r e s t with a v e r t i c a l p r o f i l e

as in F igure 3 -2 . To determine whether the d i s t r i b u t i o n s o f low

perching spec i es are modulated by compet i t i on with high perchers, I

examined spe c i e s d i v e r s i t y and perching pat terns in an adjacent study

p l o t . This area was dominated by S e l a g i n e l l a sp. ( S e l a g ine l l a c eae ) , a

short fern a l l y . Between 40 cm and 250 cm the dens i t y o f l eaves was

much lower than in the l a r g e r study p l o t . Above 2.5 m l e a f dens i ty

increased in both a r e a s .

Xes tob la t ta , E. u n i s t i l a t a , E. r o t h i , I m b l a t e l l a , and Car ib lat ta

were s i g n i f i c a n t l y underrepresented in the S e l a g i n e l l a p l o t . The

abundance o f Ek invo l u c r i s , Nesomy lacr i s , and r e f l e x a did not

d i f f e r in the two p l o t s .

( 6 ) I nd i v i dua l Va r i a t i ons in Perch Height

57

S ince marked cockroaches were recaptured r e p e a t e d l y a t d i f f e r e n t

h e i g h t s , I t e s t ed whether the v a r i a t i o n s in the wi th in s p e c i e s

d i s t r i b u t i o n s ( F i g . 3-1) might be a t t r i b u t e d to d i f f e r e n c e s in he i gh t

p r e f e r e n c e s between or w i th in i n d i v i d u a l s on d i f f e r e n t n i g h t s . Data on

perch h e i g h t s between 20.00 and 21.00 hrs f o r males o f th r ee spec i e s

were a n a l y z e d . This t ime per iod encompassed the g r e a t e s t numbers o f

r e c a p t u r e s f o r which such data were a v a i l a b l e . The v a r i a t i o n s in he i gh t

d i s t r i b u t i o n s were ma in l y due t o l a r g e * v a r i a t i o n s wi th in i n d i v i d u a l s

( T ab l e 3 - 2 ) , At 20.00 hr a marked X^. c a n t r a l l i may perch a t 20 cm on

one n i gh t and at 150 cm at the same t ime on another n i g h t . I have no

ev idence to suggest t ha t i n d i v i d u a l he i gh t p r e f e r ences c on t r i bu t e t o

v a r i a t i o n in the s p e c i e s h e i g h t d i s t r i b u t i o n .

( 7 ) V i s i on and Height S e l e c t i o n

Of the two v a r i a b l e s ( v i s i o n , h e i g h t ) examined in four c o n d i t i o n s ,

changes in he i gh t a f f e c t e d the dura t i on o f perching most s i g n i f i c a n t l y

( T a b l e 3 - 3 ) . Normal and b l inded males moved down from high perches more

f r e q u e n t l y than males p laced at 25 cm. I i n t e r p r e t these r e s u l t s to

i n d i c a t e tha t males a t 100 cm employ non-v i sua l sensory cues in

o r i e n t i n g t o more p r e f e r r e d lower p e r c h e s .

DISCUSSION

58

( 1 ) Why Perch ?

Amongst the more l i k e l y funct ions o f perching in cockroaches are a )

predator avo idance , b ) s e l e c t i o n o f pre fe r red s t ruc tu ra l ( p h y s i c a l )

m i c r o h a b i t a t s , c ) f e e d i n g , and d ) o r i e n t a t i o n to mates .

a. Predator Avoidance

That perching on f o l i a g e may be a predator avoidance s t ra t egy i s

suggested by the high a c t i v i t y o f ground dwe l l i n g ( s p i d e r s , an t s , f r o g s )

and f l y i n g ( b a t s ) p redators at n i g h t . B l a t t e l l i d cockroaches comprise

23% and 92% o f the r e s p e c t i v e d i e t s o f Austral ian Pi no p i s and Menneus

net cas t ing sp ide r s (D inop idae ) (Aust in and B l e s t , 1979) . Cockroaches

thus may enhance t h e i r chances f o r surv i va l by moving out o f the

l e a f - l i t t e r and onto f o l i a g e a t n i g h t .

Spiders in the C ten idae , Lycos idae , and Pisauridae perch on l e a v e s

in banana and co f f e e p l a n t a t i o n s (Barth and Sey far th , 1979) and in the

La Selva f o r e s t ( p e r s . o b s . ) . Prey l o c a l i z a t i o n in these sp iders i s

transduced mainly through low frequency v i b r a t i o n s emanating from the

prey and transmit ted at l e a s t 25 cm. across a l e a f (Barth and Sey f o r th ,

1979)* Presumably, the prey may d e t e c t such s i gna l s from the

approaching s p i d e r . Cockroaches t y p i c a l l y perch at the edges o f l e a v e s ,

and as a spider approaches , the cockroach assumes an a l e r t s t i l t

pos tu r e . S l i g h t v i b r a t i o n o f the substratum e l i c i t s e vas i v e responses ,

such as running r a p i d l y under the l e a f ( as in Imb la te l l a and

C a r i b l a t t a ) , abandoning the perch e i t h e r by f l y i n g or g l i d i n g to a new

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perch ( e . g . , X e s t o b l a t t a , Epilampra r o t h i ) , jumping d i r e c t l y in to the

l e a f - l i t t e r ( e . g . , jL_ i n v o l u c r i s ) , or "p lay ing dead" ( e . g . ' , H.

r e f l e x a ) . Hard, non-resonat ing surfaces as t r e e - t runks and the ground

are i n f e r i o r f o r t h i s t ype o f predator d e t e c t i o n system.

The e a r l y morning m i g ra t i on to ground and f o l i a g e h id ing p laces i s

probab ly in response to predat ion by v i s u a l predators ( l i z a r d s , b i r d s )

above ground. Most s p e c i e s o f cockroaches are we l l camouflaged in

l e a f - l i t t e r but r e l a t i v e l y conspicuous on green l e a v e s . This pattern o f

v e r t i c a l m ig ra t i on i s s i m i l a r to tha t o f zooplankton which evade v i s u a l

predators by spending the day in deepe r , darker waters (Hutchinson,

1967) . La r g e , conspicuous l a t e i n s t a r gypsy moth l a r v a e (Lymantria

d i s p a r ) e x h i b i t a d i e l m ig ra t i on to the bases o f host t r e e s , poss ib l y t o

avoid d iurna l bird predat ion in the canopy (Leonard , 1970).

b . Microhab i ta t P re f e r ences

Perching at s p e c i f i c he i gh t s may be a form of microhabi tat s e l e c t i o n

r e l a t e d to p h y s i o l o g i c a l c o n s t r a i n t s . The cockroach Arenivaga s p .

(Po l yphag idae ) e x h i b i t s c i r cad i an and seasonal v e r t i c a l movements

through the sand in the Colorado dese r t in Ca l i f o rn i a (Hawke and Fa r l e y ,

1973; Edney e t a l . , 1974 ) . The a c t i v i t y pat terns o f f ana les and

immatures c o r r e l a t e w i th temperature and humidity . S i m i l a r l y , in

Ectobius ( B l a t t e l l i d a e ) , a temperate f o r e s t and grassland cockroach,

when low temperatures p r e v a i l during the preceeding n i g h t , males s h i f t

t h e i r above-ground a c t i v i t y to l a t e a f t e rnoon ( D r e i s i g , 1971) . In both

s p e c i e s , m e t e o r o l o g i c a l f a c t o r s seem to determine the time and p lace

where a c t i v i t y o ccurs .

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Temperature , humid i t y , and wind measurements in the t r o p i c a l

r a i n - f o r e s t covary w i th both he i gh t and time o f day (R i chards , 1952;

Scha l . 1982 [Chapter 4 ] ) . P h y s i o l o g i c a l s tud ies o f temperature

t o l e r a n c e ( A p p e l , 1982) and b e h a v i o r a l s tud ies o f temperature and

humidi ty p r e f e r e n c e s o f s e v e r a l cockroach spec i es ( s ee Cornwell f 1968)

r e v e a l t h a t many s p e c i e s s e l e c t narrow environmental r anges , though they

may t o l e r a t e s i g n i f i c a n t l y g r e a t e r r a n g e s . Hence, d i f f e r e n c e s in perch

h e i g h t s o f s p e c i e s , s e x e s , and l i f e - s t a g e s may r e f l e c t m i c rohab i t a t

s e l e c t i o n based on p h y s i o l o g i c a l t o l e r a n c e . The problem of mate - f ind ing

r e s u l t i n g from h a b i t a t d i f f e r e n t i a t i o n ( e s p e c i a l l y in perch he i gh t ) o f

the sexes i s l e s s s eve re in mob i l e animals than in p lant communities

( s e e Meagher, 1980 ) , thus pe rm i t t i ng g r e a t e r e c o l o g i c a l d i v e r g e n c e .

I d id not determine whether i n d i v i d u a l s s e l e c t s p e c i f i c he i gh ts

above the ground or a b i o t i c f a c t o r s which covary with he i gh t ( a s

t empera tu re , humid i ty , r e f u g i a , and f o o d ) .

c . L o c a l i z a t i o n o f Food and Feeding

Whi le on f o l i a g e , cockroaches feed on e p i p h y l l i c a l g a e , b r yophy t e s ,

l i c h e n s , p o l l e n , s p o r e s , and o ther o rgan i c matter trapped on the

sur faces o f l e a v e s . Schal and Be l l (1982a ; [Chapter 51) reported that

X e s t o b l a t t a hamata and o ther s p e c i e s (unpubl ished) feed on b i rd

d r opp ings , f r u i t s , and f l a k e s o f shed ba rk , which are in t e r cep ted on the

su r f a c e s o f l e a v e s . These s t u d i e s (and r e l a t e d work wi th

scarabs - Howden and N e a l i s , 1978) i n d i c a t e that perching on l e a v e s

enhances food f i n d i n g , food l o c a l i z a t i o n and f eed ing in seve ra l s p e c i e s

o f c o ck roaches .

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The he i gh t s at which cockroaches perch co r r e l a t e we l l with t h e i r

r e s p e c t i v e d i e t s . invol u c r i s adu l ts perch c l ose to the ground and

feed main ly on d e t r i t u s in the l e a f - l i t t e r . I n t e r e s t i n g l y , males which

perch a t he i gh ts up t o 50 cm ( F i g . 3-1) supplement t h e i r d i e t s with

e p i p h y l l i c m a t e r i a l , whereas f emales which are more common in the

l e a f - l i t t e r r a r e l y graze on su r f a c e s o f l e a v e s . Imb la t t e l l a and

Car ib la t ta feed almost e x c l u s i v e l y on l e a f tr ichomes, blue green a l g a e ,

l i v e r w o r t s , and spores which they obta in from leaves whi le perch ing .

Xes tob la t ta and Epilampra, except E^ i n v o l u c r i s , feed on fermenting

f r u i t s trapped on under story l e a v e s and on the ground. Poss ib l y , a

f i n e l y r e so l v ed separation o f cockroaches may operate above ground based

on the d i s t r i b u t i o n o f e p i p h y l l s . Ep iphy l l s are most common within 1-2

m of the ground and the i r spec i es composit ion changes markedly with

height wi th in t h i s zone (B . Ben t l e y , p e r s . comm.).

. O i t o g ene t i c d i f f e r ence s in h e i g h t s a lso c o r r e l a t e with t roph ic

d i f f e r e n c e s within spec i e s . Whereas adul ts are thought to be n i t rogen

l im i t ed as evidenced by the high r a t e o f oocyte r esorp t i on and the

m o b i l i z a t i o n o f stored uric acid in natura l populat ions (Schal and B e l l ,

1982a) , nymphs o f Xes tob la t ta , N y c t i b o r a , Mega lob la t ta , and probably

many other spec ies ( see Roth and A l sop , 1978) secre te prote inaceous

de f ens i v e m a t e r i a l s (Schal e t a l . , 1982 ) , suggesting tha t n i t rogen i s

not as l i m i t e d for ground-dwel l ing nymphs.

d. L o c a l i z a t i o n o f Mates

In Chapter 4 (Scha l , 1982) I propose a convec t i ve pheromone plume

model to account for d i f f e r e n t i a l v e r t i c a l , sexual s t r a t i f i c a t i o n in

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cockroaches . Females emit v o l a t i l e sex pheromones which mix v e r t i c a l l y

in c o n v e c t i v e and turbu lent edd i e s and reach c o n s p e c i f i c males which are

on the ave rage higher than the f emales . Since convect ion plumes

o r i g i n a t e on l e a f su r f a ces (Gates and Bened ic t . 1963) , and dense

v e g e t a t i o n r e t a r d s pheromone f l o w ( see Aylor e t a l . , 1976), perching on

l e a v e s may enhance the ma te - f i nd ing process (Scha l , 1982) .

My r e s u l t s ( F i g . 3-2) and other s tud i e s o f v e r t i c a l v e g e t a t i on

p r o f i l e s ( l e a f area measurements) o f dense t r o p i c a l f o r e s t s suggest that

a "chemica l communication channe l " may e x i s t up to 2 m. above the

ground. Within t h i s c o r r i d o r the v e g e t a t i o n i s more sparse , c l o s e to

l e a f - l i t t e r s h e l t e r s , and r i c h in e p i p h y l l s and fermenting f r u i t s on

which cockroaches f e e d . Un fo r tuna te l y , because nothing i s known o f the

chemical nature o f sex pheromones o f f o r e s t cockroaches , I do not know

i f v e r t i c a l s t r a t i f i c a t i o n p a r t i t i o n s t h i s stratum among spec ies with

s im i l a r pheromones. In ]L_ hamata and c a n t r a l l i , d i f f e r e n c e s in the

temporal and spa t i a l pa t t e rn ing o f d iurna l c y c l e s o f perch ing , c a l l i n g ,

and mating may be adequate t o i s o l a t e the two spec i es even i f they

u t i l i z e s i m i l a r or i d e n t i c a l sex a t t r a c t a n t s ( see be low; a l s o , Roelo fs

and Carde, 1971, for a s im i l a r s i tua t i on in L e p i d o p t e r a ) .

( 2 ) Morphology and Perching

In the " open" t r o p i c a l wet f o r e s t , the n i g h t l y he ight d i s t r i b u t i o n s

o f the ten cockroach s p e c i e s seem to c o r r e l a t e p r imar i l y with modes o f

locomot ion and with body s i z e . However, the c l o s e c o r r e l a t i o n between

he ight and body s i z e may be a consequence o f the r e l a t i o n between body

63

s i z e and escape behav i o r , maneuverab i l i t y , and other behaviors which are

d i f f e r e n t i a l l y se lec ted for a t d i f f e r e n t he i gh t s . Moreover, I do not

know whether a l l w ing less spec i e s occur c l ose to the ground, but

perching h igher may be i n e f f i c i e n t i f v o l a t i l e pheromones are u t i l i z e d

as descr ibed above .

Nyct ibora noct ivaga ( B l a t t e l l i d a e ) and Blaberus co losseus

( g i gan teus ) (B labe r idae ) , two l a r g e , winged spec i e s , occur on t r e e

trunks above the present sampling range . However, the apparent r e l a t i o n

between s i z e and perch he ight i s not without except ions . hamata

i nd i v i dua l s perch lower than the smaller c a n t r a l i i . E. a z t e ca , o f

s imi lar s i z e to r o th i , seems to range up to the f o r e s t canopy.

In communities which are structured on the bas is o f body s i z e , the

l a t t e r c o r r e l a t e s we l l with food s i z e ( e . g . , Hespenheide, 1973). In the

present study a l l spec i es seem to forage on s imi lar sized food, but i t s

l o c a t i o n may vary from the ground up to the canopy. In t h i s r e s p e c t ,

the studied cockroach community resembles other g ra z ing , p l an t , and

f i l t e r - f e e d i n g communities.

E c o l o g i c a l l y , cockroaches do not separate along higher taxonomic

l i n e s in t h i s study. There are no apparent cons is tent d i f f e r enc e s in

hab i ta t u t i l i z a t i o n between the b l a t t e l l i d a e and the Blaberidae (both

are most abundantly r e p r e s e n t e d ) . By incorporat ing other hab i t a t s

(unpublished o b s e r v a t i o n s ) , a c l e a r e r phylogenet ic pattern emerges.

Members o f the B l a t t e l l i d a e are found mainly in "open" f o r es t h a b i t a t s ,

whereas b l abe r i d cockroaches are more common in " c l o s ed " microhab i ta ts

such as c a v e s , ho l low t r e e s , r o t t i n g l o g s , b i rd nes t s , and in

underground c a v i t i e s . With the except ion o f Epilampra, few b l a b e r i d s

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occur in the f o r e s t above "1 m. Epilampra r epresen ts a phy logenet ic

in t e rmed ia t e between the B l a t t e l l i d a e and the B laber idae (Roth t 1970b;

Fisk and Scha l , 1981 [Chapter 2 ] ) .

I t remains to be determined whether the preva lence o f b laber id

cockroaches in " c l o s e d " hab i t a t s i s r e l a t e d to t h e i r ovov iv iparous

r ep roduc t i v e mode ( b l a t t e l l i d s are o v i pa rous ) and consequent ly to long

pe r i ods o f i n t e rna l incubat ion o f embryos by the f emale . Caves o f f e r a

n u t r i t i o n a l l y more s t a b l e hab i ta t than "open" t r o p i c a l f o r e s t s .

Accumulated ba t guano r ep resen t s an abundant source o f amino n i t rogen

which i s l i m i t i n g in the f o r e s t . Hence, a v a i l a b i l i t y o f usable n i t rogen

may have s e l e c t ed for the d ivergence o f b laber ids and b l a t t e l l i d s in

modes o f communication, s o c i a l o r g a n i z a t i o n , and parenta l s t r a t e g i e s .

In the B l a t t e l l i d a e , u r i c acid con t r ibuted by males to females i s

t r ans f e r r ed in to the eggs and i s used as a source o f n i t rogen (Schal

and B e l l , 1982a [Chapter 5 1 ) .

( 3 ) Temporal P a r t i t i o n i n g

I t i s sometimes e a s i e r to document d i f f e r e n c e s in spa t i a l hab i ta t

use than d i f e r e n c e s in temporal a c t i v i t y pa t t e rns . Two spec ies which

o ve r l ap s p a t i a l l y and t empora l l y may in f a c t at the same time segregate

on a f i n e r behav io ra l l e v e l . For i n s t a n c e , when spec ies A f e e d s ,

spec i es B c a l l s ; when A c a l l s , B mates, e t c . Such temporal d i f f e r e n c e s

in a c t i v i t y seem to occur in the two c l o s e l y r e l a t e d Xestob lat ta

s p e c i e s . X^ hamata mates f o r 248±18.5 min (N=9) and pa i r s do not

couple u n t i l c a . 23-00 hr (Schal and B e l l , 1982a). On the other hand,

65

X. c a n t r a l l i matings usua l l y beg in e a r l i e r ( c a . 21.00 hr ) and l a s t c a .

3 hours . The two spec ies have s imi la r feeding pat terns and requirements

(Schal and B e l l , in manusc r ip t ) , and females o f both spec ies engage in

" c a l l i n g " or pheromonal a t t r a c t i o n o f males (Schal e t a l . , in

p r epara t i on ) . The t iming o f matings and perching a c t i v i t y in

Xes tob la t ta seem to represent a case o f "nonsynchronous spa t i a l o ve r l ap "

(Schoener , 1970) by two s p e c i e s .

Temporal ly staggered h a b i t a t u t i l i z a t i o n by re la ted spec ies may

sometimes be r e l a t ed to noncircadian f a c t o r s . For ins tance , r a i n f a l l

may e l e v a t e or depress the l e v e l o f a c t i v i t y or abundance

(conspicuousness ) o f some spec i e s and not o t h e r s . S i m i l a r l y , seasonal

changes in a c t i v i t y may r e s u l t from d i f f e r e n c e s in mo is ture ,

t emperature , a v a i l a b i l i t y o f f o o d , s h e l t e r , e t c . Wolda and Fisk (1981)

documented changes in the abundance o f cockroaches in s i t e s with a

pronounced dry season and in r e l a t i v e l y aseasonal s i t e s in Panama.

Un for tunate l y , the use o f l i g h t t raps precluded examination o f many

under s t o r y spec i es which are not a t t rac ted to l i g h t s .

I m b l a t t e l l a and Car i b l a t t a are good candidates for e luc ida t ing

seasonal e f f e c t s because the th r ee spec ies o v e r l ap cons iderab ly in the i r

d i e l a c t i v i t y pa t t e rns ( F i g . 3-9) and s p a t i a l hab i t a t ( F i g . 3 -D t and

are s im i l a r in morphology and behav io r . Cor re la t i ons o f r a i n f a l l and

spec i e s abundance betweeen March and July 1979 ind i ca t e that _ I . impar

and Cj_ imi tans respond to proximate changes in r a i n f a l l (unpublished) .

The abundance o f 1^ n . s p . "G" dec l ined during t h i s period

i r r e s p e c t i v e o f r a i n f a l l , suggest ing a more genera l seasonal response.

Similar pa t t e rns seem to e x i s t between E. r o t h i and E. u n i s t i l a t a but

6 6

much more i n t e n s i v e i n v e s t i g a t i o n s are necessary to e luc i da t e these

r e l a t i o n s h i p s .

( 4 ) Niche Me t r i c s and Competition

The use o f niche o v e r l ap and breadth measures as i n d i c e s o f

c ompe t i t i on ( e . g . , Gorton, 1980) may be mis leading because the

r e l a t i o n s h i p s between them are not known (see Abrams, 1980) . Lawlor

( 1 9 8 0 ) , Abrams (1980 ) , Schoener ( 1 9 7 4 ) , and o thers argue that use o f

o v e r l a p measures as subs t i tu t e s f o r compet i t ion c o e f f i c i e n t s may

o v e r e s t ima t e compet i t i on . Unrelated spec ies may share common

n o n - l i m i t i n g resources and hence o v e r l a p e x t e n s i v e l y . The r e l a t i v e

r a t e s o f resource renewal determine the importance o f the resource in

compet i t i on ( L a w l o r , 1980).

Mechanisms for i n t e r f e r e n c e compet i t i on in cockroaches i n v o l v e

a g o n i s t i c i n t e r a c t i o n s ( e . g . , Schal and B e l l , 1982b), yet I observed few

such c o n t e s t s f o r perches . I n t e r s p e c i f i c and intrasexual encounters on

f o l i a g e most commonly r esu l t ed in avoidance behavior , except when

n a t u r a l l y or exper imenta l l y ba i t ed with f o od . Moreover, the r e l a t i v e l y

low abundance o f some spec i e s in the S e l l a g i n e l l a community did not

r e s u l t in expansion o f perch he i gh t d i s t r i b u t i o n s o f other s p e c i e s .

In the present paper the presence or i n t e n s i t y o f compet i t ion for

perches i s unknown. Ra in - f o res t perches seem to be abundant at a l l

h e i g h t s and during a l l seasons, but I do not know what c o n s t i t u t e s a

s u i t a b l e perch and whether perches a t d i f f e r e n t he ights have d i f f e r e n t

f i t n e s s v a lu e s for cockroaches . I t i s premature to draw i n f e r ence s

67

about i n t e r s p e c i f i c competit ion from the present da ta . I t i s a lso

important to recogn ize that I measured only two major niche axes :

perching he ight and perching t i m e . No doubt other dimensions separate

seemingly over lapping species and reduct ion to v e r t i c a l and temporal

o ve r l ap measures may ignore a d d i t i v e and m u l t i p l i c a t i v e in t e rac t i ons

among resource axes (May, 1975). For example, I do not know whether

seasonal s h i f t s in habitat use ( o ther than changes in species abundance)

occur in any o f these spec i es , how the a v a i l a b i l i t y o f food ( i . e . ,

f r u i t i n g phenology o f p lants ) modulates over lap i n d i c e s , or on a f i ne r

l e v e l , what I de f ine as the v e r t i c a l d i s t r i bu t i on o f females of spec ies

A may in f a c t comprise severa l p h y s i o l o g i c a l l y d i s t i n c t subsamples. A

case in po int i s the observat ion that females remain in the l e a f - l i t t e r

or c l ose to the ground when ready to o v i p o s i t .

F i e ld observat ions ind i ca t e that sexual pa r t i t i on ing among

c o n s p e c i f i c s i s r e la ted to enhanced p r o b a b i l i t i t e s o f f inding mates

( Scha l , 1982 [Chapter 4 ] ) . Hence, low ove r lap measures between females

and males more l i k e l y r e f l e c t sexual se l ec t i on and d i f f e r i n g r o l e s in

mate a c q u i s i t i o n than reduced in te rsexua l compet i t ion. This study

i nd i ca t e s tha t these populat ions o f cockroaches are structured on

severa l l e v e l s . With respect to sex , the v e r t i c a l d i s t r i bu t i ons o f

spec i es r epresent the combined v e r t i c a l ranges o f males and females

which in f a c t s t a t i s t i c a l l y d i f f e r from one another. With respect to

age , adu l t s and juven i l e s occupy d i f f e r e n t v e r t i c a l and in some cases

a lso ho r i z on ta l ranges . The i n t e r a c t i o n o f age with sex i s documented

by the p r o g r e s s i v e l y higher mean perch he ight o f nymphs with increas ing

age , and the d i f f e r e n c e s between l a t e instar males and females . I

68

conclude tha t an understanding o f the h a b i t a t o f d i f f e r e n t c l a s s e s o f

i n d i v i d u a l s w i th in a popu la t i on i s e s s e n t i a l for d i scuss ions o f

community s t r u c t u r e .

ACKNOWLEDGEMENTS

I thank Gard Ot is who introduced me to Costa R ica , and the

Organ i za t i on f o r T r o p i c a l S tud ies who prov ided l o g i s t i c support at the

La Selva f i e l d s t a t i o n . Gunt^er Se e l i n g e r a ss i s t ed with moni tor ing

a c t i v i t y in the l a b o r a t o r y and was an I n s p i r a t i o n in the f i e l d . I thank

Michael Grayum for i d e n t i f y i n g p lan ts in my p l o t s . R. Holt for a

c r i t i c a l d i s c u s s i o n o f n i che m e t r i c s , and K. Armitage , R. Jander, C

Michener , and 0. Taylor f o r r e v i ew ing t h i s chap t e r . P a t r i c i a Estes

a s s i s t e d in input o f da ta for computer a n a l y s i s and Frank Fisk

i d e n t i f i e d voucher spec imens . Supported in part by NSF grants

BNS 80-06284 and BNS 77-24898 to Dr. W.J. B e l l and DEB 80-07556 to WJB

and me, and a Sigma Xi G ran t - i n -A id o f Research t o me.

Table 3 - 1 . Comparison of trap catch at four he ights .

Height

Species Ground 0.5 m 3 m 1 0 m

Epilampra invo lucr i s males 15 3 0 0

females 21 0 0 0

Nesomylacris sp . males 22 9 0 0

females 25 2 0 0

Hyporhicnoda re f l exa males 9 1 0 0

females 12 0 0 0

Xestoblatta hamata males 1 1 1 1 0

females

co 6 0 0

Epilampra ro th i males 12 27 6 1

females 5 1 1 0

nymphs 106 1 3 0 0

Xestoblatta c a n t r a l l i males 12 22 8 0

females 7 25 1 0

P lec topter ine species males 3 3 3 1

females 4 2

on 0

nymphs 5 11 2

70

Epilampra i n v o l u c r i s males

Source d . f . S .S .

Between i n d i v i d u a l s 5 250

Wi th in i n d i v i d u a l s 11 476

Epilampra r o t h i males

Source d . f . S .S .

Between i n d i v i d u a l s 9 17352

Within i n d i v i d u a l s 22 27443

Mean Squares F Ratio

50 1.157

43

Mean Squares F Ratio

1928 1.546

1247

P

0.389

P

0.194

X e s t o b l a t t a c a n t r a l l i males

Source d . f . S. S.

Between i n d i v i d u a l s 1451

Mean Squares F Ratio P

726 1.801 0.244

Within i n d i v i d u a l s 2417 403

Tab l e 3 - 2 . Comparison o f i n d i v i d u a l and s p e c i e s v a r i a t i o n s in

he ight p r e f e r e n c e s .

71

Table 3-3 . Time that experimental Epilampra invo lucr i s males i

remained on a l e a f a f t e r r e l e a s e .

Experimental Height

Condition (cm)

N mean ± SEM Signi f icance

(minutes) (P<0.05)

Normal

Blinded

Normal

Blinded

25

25

100

100

15 26.7 ± 4. 13

15 23-7 ± 3-67

15 8-7 ± 1.24

15 7.7 ± 0.96

a

a

b

b

Recorded at 5 minute i n t e r v a l s .

Condit ions labeled with d i f f e r e n t l e t t e r s are d i f f e r en t

72

ure 3 - 1 . V e r t i c a l d i s t r i b u t i o n s o f s p e c i e s , s e x e s , and l i f e - s t a g e s

o f cockroaches . The o r d i n a t e i s perch height in cm. The sample

s i z e f o r each group i s next to the r e s p e c t i v e h is togram. The mean

spec i e s perch h e i g h t s are graphed between the d i s t r i b u t i o n s o f the

males and f ema les . S t a t i s t i c a l l y d i f f e r e n t (P<0.05, Student 1 s

t - T e s t o f l o g transformed data and Wilcoxon Rank Sum Test ) spec i e s

d i s t r i b u t i o n s are l a b e l e d with d i f f e r e n t l e t t e r s (above spec ies

mean) . I m b l a t t e l l a and Car i b l a t t a nymphs are grouped together

( p l e c t o p t e r i n e s ) because I could not i d e n t i f y the s p e c i e s .

73

Epilampra involucris Nymphs

i >1.5cm j1-1.5cmi0.5-1cm 22 -L 39

, females

111

20 40 20 40% 20 40 60

31

20 40 60 20 40 60%

Xestoblatta hamata

Epilampra unistilata

males

74

75

ure 3 -2 . V e r t i c a l v e g e t a t i o n p r o f i l e o f the study a r ea . A 400 nT

p l o t was d i v i d ed i n t o 1 x 1 m squares which in turn were subdivided

i n t o 25 areas each . Two 20 x 20 era squares were se l ec ted randomly

2

w i th in each 1 m and I recorded the presence or absence o f l eaves

w i th in 5 cm o f a 3 m v e r t i c a l s t i c k pos i t i oned in the i r c e n t e r s .

This p r o f i l e i s the average o f 800 i n d i v i d u a l 3 ra v e r t i c a l p r o f i l e s .

76

o

CO

o O

Ü

o X

O o - Q

^ o s

" 5 o > c o 0 3

S O Ü

o ®

— r -

o c o CM

o

CM

o o CM

O CD

""T" O CM

O CO

O

( U J O ) m B i a n

77

ure 3 - 3 . R e l a t i on between v e r t i c a l o v e r l a p ( equa t i on 1) and over lap

c o r r e c t e d f o r the a v a i l a b i l i t y o f p e r ches ( s e e t e x t ) ,

each O r e p r e s e n t s 2 c o r r e l a t i o n s ,

each (•) r e p r e s e n t s 4 c o r r e l a t i o n s ,

each # r e p r e s e n t s 6 c o r r e l a t i o n s .

A t o t a l o f 90 c o r r e l a t i o n s are p r e s e n t e d . 9 f o r each o f the 10

s p e c i e s .

78

° 8 ° O O

0 °

o

o o

(S> o o

o o

o

8 o '

o o o o

o o

- i 1 1 1 1 t: 1 Z 1 r

00 CD * <N

dBiJeAO aipru iB^eds

oo O »

0

>

o

O c o SZ

' 2 c

CO

9 -CO

" O

0

ü 0

• o

o

79

F i gure 3-4 . Re l a t i onsh ip between d i f f e r e n c e s in spec ies mean he ight and

v e r t i c a l o v e r l a p , middle spec i e s are L hamata, X. c a n t r a l l i f E.

u n i s t i l a t a , and r o t h i . Within assemblages are comparisons o f

s p e c i e s w i th in each assemblage ( e . g . , E._ u n i s t i l a t a v s .

Nesomy lac r i s . E. r o th i v s . E. u n i s t i l a t a ) .

80

82

. 5 s • • ó o S « *

(U10) iM6!QM U I - 9 0 U 8 J 9 ^ ! a

83

ure 3-6. Dendrogram of ecological similarity of species and

consexuals. based on overlaps in vertical distributions. Overlaps

within clusters were averaged in the amalgamation procedure.

O'Cis-u ~B||eUB|quj| -

SUB^UU! B U B | q U B Q -

j B d u n B | | O U B | q a i | -

B + B||lSjUn BJdUUB| l d3 -

miOJ B J d L U B | l d 3 -

i | | B j ; u b o B U B i q o i s e x

b . b u j b m B U ^ i q o i s e x

B x e u e J B p o u o i M i O d Á H -

' d s s u o e j A i u o s a N

s u o n j O A U ! B i d a i B | ! d 3 • 3 -

CO 0

CC

E 0)

0 - d s *u B||©MB|qui| -

S U B 1 I U J ! B + |B | q U B O -

jBduüi B|ieuB|quj|-

J||BJiUBO B U B | q O * 8 8 X -

!M;oj BJdLUBi jdg -

B ;B| i )B iun B J d u u B j i d g -

b ^ b u u b l i B U B i q o j s e x -

B X B u e j BpouoiqjodAH-

ds siJOB|XuJOseN-

s u o n | O A U i BJduuBiidg.

CO

Ctf 2

9 " d s - u B n © » B i q u i | -

s u B i i u n B ; ; B | q u B Q -

jBdtu i B||euB|quJ|-

I||BJ1UB0 B l i B | q 0 l S 9 X -

i i o o j BJduñsiTdg-

B ^ B i u s i u n B J d u J B ( i d 3 -

B|BLUBL| B U B | q 0 ^ 9 9 X "

Bxauej BpouoiqjodAH-

' d S SU0BJÁUJOS9N

s u o n | O A U i B jda iB | i d 3

CO

a CO

t I I I I I T . .

^ 6 o o o o d o o o d O

85

F i g u r e 3~>7« R e l a t i o n between mean he ight and v e r t i c a l breadth f o r

s p e c i e s and s e x e s . Boundaries f o r groups were drawn to d e l i m i t t h e

t h r e e assemb lages ; no s t a t i s t i c a l procedure was used to do s o .

• = s p e c i e s t

o = f e m a l e s .

0 = m a l e s .

(wo) iqBieq qojad U B 9 J ^

87

ure 3 - 8 . R e l a t i o n between mean he i gh t and the d i f f e r e n c e in mean

h e i g h t s o f c o n s p e c i f i c males and f e m a l e s .

88

89

F igure 3 - 9 . D i e l a c t i v i t y o f cockroaches . Comparison o f

a c t i v i t y ( consp icuousness ) in the f i e l d and locomotory a c t i v i t y in an

outdoor in s e c t a r y .

90

o o o o o o o o o o o o q o o o o o 9 9 9 9 9 9

o o o o o o o o o o o o o o o 0 0 0 0 9 9 9 9 0 CD 00 O 0¡ *t CO 00 O OÍ CV¡ «<t

. ^ T - r . - p . T - C S J C S i C N J

( D (0

o

20

10

40

30

20

104

I I . . I ftlttlfí r-T~l Ep^ampra involucris

Males i i i i

i

Epilampra involucris Females

Nesomylacris sp.

Males

Hyporhicnoda reflexa

Males

30- Euphyllodromia angustata

20- Males 10-

1 rl > 3 0 H

20

10-T

Euphyllodromia angustata

Females

H a o o o o o o o o o o o o o o o o o o o 9 9 9 9 9

20-

10

Xestoblatta cantralli Males

Xestoblatta cantralli 10-

20

10

20-I

10

r emales

Xestoblatta hamata Males

Xestoblatta hamata Females

10

Imblattella n.sp.G Mates

2 OH

10

Cariblatta imitans Males

301

20

1CH

20"

10

niinniinrl [iiill Imblatella impar

Males

11111111

Epilampra rothi Males

o o o o o o o o o 0 0 0 0 0 0 0 0 0 0 9 0 0 9 0

91

CHAPTER 4

I n t r a s p e c i f i c V e r t i c a l S t r a t i f i c a t i o n as a Mate-Finding

Mechanism in Trop ica l Cockroaches

Cockroaches in a t r o p i c a l f o r e s t s t r a t i f y v e r t i c a l l y both i n t e r - and

i n t r a s p e c i f i c a l l y along m i e rome t eo ro l og i ca l g r a d i e n t s . At n i gh t t l o w

wind speeds and unstable atmospheric c ond i t i ons r e su l t in e f f i c i e n t

mix ing o f a i r near the ground . Convect ive ascent o f warm a i r imparts

d i r e c t i o n a l i t y to the pheromone d i spe rs i on process . The occurence o f

males a t g r e a t e r he i gh t s than pheromone- emit t ing conspec i f i c f emales

appears t o be a mate - f ind ing s t r a t e g y .

INTRODUCTION

92

For a i r bo rne chemicals to be e f f e c t i v e s i gna ls in communication,

t h e i r r e l e a s e and recept ion must c o r r e l a t e with f a v o r a b l e

m i e rome teo ro l og i ca l cond i t i ons . To enhance t h e i r e f f i c i ency in f i n d i n g

pheromone-emitt ing females , males should occupy ranges a b o v e ,

o v e r l app ing , or below the females 1 v e r t i c a l ranges , depending upon the

p r e va i l i n g atmospheric c o n d i t i o n s . Because meteorological p a t t e r n s

e xh ib i t c i r c a d i a n c y c l e s , they couple the o r i en ta t i on behav i o r to

s p e c i f i c t imes during the day or n i g h t . I f , for example, buoyant

( temperature decreases with he i gh t above the ground) atmospheric

cond i t i ons p r e v a i l at n i g h t , males should occupy perches a t g r e a t e r

he ights than f ema les . Conversely, under s tab le (temperature i n c r e a s e s

with h e i g h t ) atmospheric c ond i t i ons with temperature i n v e r s i on , males

should o v e r l ap with the v e r t i c a l d i s t r i b u t i o n o f the females o r range

below them.

Dispers ion models ( e . g . , Sut ton, 1953; Bossert and Wilson, 1963;

r ev i ew : ELkinton and Carde, 1983) descr ibe plumes with center l i n e s

p a r a l l e l t o the ground and remaining at the height of the point s o u r c e .

The v e r t i c a l and hor i zonta l p r o f i l e s o f the plumes at any g i v en po int

along t h i s l i n e correspond to Gaussian d i s t r i b u t i o n s . These models

p red i c t t h a t the optimal v e r t i c a l d i s t r i b u t i o n for males should

comple te ly o v e r l a p the range o f pheromone-emitting f emales . An

exception i s a study by Fares e t a l . (1980) who discuss the i n f l u e n c e o f

m ie rometeo ro l og i ca l condi t ions on concentra t ion p r o f i l e s at d i f f e r e n t

emission h e i g h t s . They conclude tha t "pheromone communication appears

93

t o be i n e f f e c t i v e under buoyant atmospheric c o n d i t i o n s . " However, they

l i m i t t h e i r data ana l ys i s to daytime pat terns and t o d i u r n a l l y a c t i v e

i n s e c t s . A l s o , f l i g h t o f d iurna l i n s e c t s may be r e l a t ed to thermal

s t r e s s in mid-day r e s u l t i n g in e a r l y and l a t e (b imodal ) f l i g h t a c t i v i t y ,

which happens to c o r r e l a t e we l l with s t a b l e c o n d i t i o n s . Fares e t a l .

(1980) do not address t h i s problem.

With increased i n t e r e s t in behav io ra l and b i o l o g i c a l c o n t r o l and

management o f f o r e s t i n s e c t s , i t i s important t o descr ibe the t r a n s p o r t

mechanisms which operate in o l f a c t o r y communication. I r e p o r t s p a t i a l

d i s t r i b u t i o n data for f o r e s t cockroaches with m ic rome teo ro l og i ca l

p r o f i l e s and show that v e r t i c a l s t r a t i f i c a t i o n i s important in

m a t e - f i n d i n g .

RESULTS and DISCUSSION

I found tha t the cockroach community a t Finca La Selva in Costa Rica

( see Ho ldr idge e t a l . , 1971 f o r s i t e d e s c r i p t i o n ) s t r a t i f i e d v e r t i c a l l y

both i n t e r - and i n t r a s p e c i f i c a l l y . I n t e r s p e c i f i c and demographic

separat ion was discussed in Chapter 3. Resource p a r t i t i o n i n g due t o

sexual dimorphism i s l i k e l y to occur in seve ra l spec i es ( e . g . , Epilampra

i n v o l u c r i s , and Hyporhicnoda r e f l e x a ) , where the females are e i t h e r

l a r g e r than the males or are w i n g l e s s . However, t h i s mechanism does not

account f o r the c ons i s t en t occurrence o f males higher than c o n s p e c i f i c

females r e g a r d l e s s o f the morphology or s i z e o f the s exes .

I hypo thes i z e that sexual s t r a t i f i c a t i o n enhances the e f f i c i e n c y o f

males in o r i e n t i n g to pheromone-emitt ing f ema les . This mechanism w i l l

94

ope ra t e bes t when temperature lapse p r o f i l e s r e su l t in convec t i ve ascent

o f a i r (and a i rbo rne chemica ls ) near the ground.

Contrary to what i s expected in the canopy and above the f o r e s t

( R i c h a r d s , 1952 ) , daytime temperature invers ion i s fo l lowed by n ightt ime

temperature l apse within 2 m above the ground ( F i g . 4-1, see a lso

Me lpar , 1969 ) . The wind p r o f i l e ( F i g . 4-2) i s s imi lar to r e s u l t s

obta ined by o ther r esearchers (Evans, 1939; Ge iger , 1965; A l l en e t a l . ,

1 9 7 2 ) , but the wind speeds recorded in the t r op i ca l f o r e s t a t n ight are

a t l e a s t an order o f magnitude smaller than those reported from other

f o r e s t t y p e s .

The i n t e r a c t i o n o f v e r t i c a l thermal g rad ients and mechanical aspects

o f the wind p r o f i l e i s described by the Richardson number, R ( e . g . ,

Thorn, 1975 ) . I t i s a measure o f the s t a b i l i t y o f the atmosphere near

t h e ground. In the present study, temperature lapse and low wind speeds

near the ground at n ight r e s u l t in l a r g e negat i ve R v a l u e s . Free

c onvec t i on predominates c l o s e to the ground; buoyant a i r o f r e l a t i v e l y

l o w d e n s i t y moves v e r t i c a l l y into denser , coo ler air r e su l t i ng in

e f f i c i e n t v e r t i c a l mix ing . Higher above the ground f r e e convect ion and

wind-generated edd ies c o e x i s t to form a hybrid turbulence regime ca l l ed

mixed c o n v e c t i o n .

The d r i v i n g f o r c e o f the nightt ime thermal convection i s d i r e c t l y

p r opo r t i ona l t o the d i f f e r e n c e in temperature between the two mixing

l a y e r s o f a i r . As a i r r i s e s , i t s temperature excess over that o f i t s

new environment i n c r e a s e s , and the r e f o r e the buoyant d r i v i n g force

i n c r e a s e s . Hence, a c onvec t i v e plume w i l l a cce l e ra t e upward un t i l

slowed by entrainment (m ix ing ) or unt i l i t meets a l aye r o f s tab le a i r .

95

The observed temperature d i f f e r ences decrease per unit d is tance o f

ascent ( F i g . 4 - 1 ) . There fo re , both entrainraent and s t a b i l i t y at higher

l e v e l s decrease the ra te o f upward movement o f the plume.

•Visual r epresenta t i ons o f plumes from point sources o f a r t i f i c i a l ,

nonbuoyant smoke ( F i g . 4 - 3 ) indicate that the v e r t i c a l component i s

f r equen t l y more s i g n i f i c a n t c lose to the ground where l a r ge temperature

d i f f e r e n c e s and low wind speeds predominate. At higher l e v e l s the

ho r i z on ta l component accounts for most o f the a i r movement as

entra inment , increased wind speeds, and a sh i f t to thermal s t a b i l i t y

i n t e r a c t to reduce the v e r t i c a l f low.

I f r e l a t i v e l y small v e r t i c a l temperature grad ients impart

d i r e c t i o n a l i t y to a i r movement, then a behavioral response which does

not occur under v e r t i c a l l y isothermal condit ions ( that i s , subthreshold

pheromone concent ra t i ons ) ought to be e l i c i t e d in males downwind in a

temperature g r a d i e n t . I i ns ta l l ed a 1 centigrade degree v e r t i c a l

g rad i en t over a d i s tance of 60 cm with res is tance wire and two

temperature r e gu l a t o r s ( Y e l l ow Springs Instruments models 71 and 7 3 ) . A

continuous output o f the temperatures was provided by a two-channel

- 6

s t r i p char t recorder (Ester l ine-Angus Speed Servo 2 ) . I used 5 x 1 0

fig o f s yn the t i c ( +/ - ) Periplanone B (Adams e t a l . , 1979) adsorbed onto

a 1 cm Whatman number 1 f i l t e r paper to e l i c i t sexual responses in P.

americana males in a screen cage above the pheromone source. The t e s t

recorded the number o f t imes in 30 second in t e r va l s that the males

crossed a l i n e b i s e c t i n g the f l oo r o f the cage. Each t e s t was 4

minutes. I performed 10 t e s t s in isothermal and ten in temperature

lapse c o n d i t i o n s .

96

ACKNOWLEDGEMENTS

I thank R .C Sapp (Department o f Phys ics , Univers i ty o f Kansas) for

In i so thermal ( n e u t r a l ) condi t ions the Periplaneta americana sex

pheromone d id not e l i c i t searching in ma les ; no courtship responses were

o b s e r v e d . However, when temperature was made to decrease with height ,

and the pheromone was introduced below the males, t h e i r locomotion

increased s i g n i f i c a n t l y ( P < 0 . 0 1 ) , and the complete courtship sequence of

r ap id antennal movement, s t i l t walking, wing r a i s i n g , and wing fanning

was e l i c i t e d . C l e a r l y , the thermal gradient imparts a new o

d i r e c t i o n a l i t y t o the a i r f low. The 360 emission angle o f Fickian

d i f f u s i o n dec r eases t o a narrow v e r t i c a l plane in the d i r e c t i on o f the

ma l e s . Hence, more molecu les per unit volume o f a i r impinge on the male

antennae, and thresho ld concentrat ions are more l i k e l y to be reached.

Silverman and B e l l (1979) found that j \ americana males tethered on

a v e r t i c a l sur face responded to sex pheromone de l i vered perpendicular ly

t o the v e r t i c a l s u r f a c e . Air without pheromone caused the males to run

up, whereas a i r cur ren ts with sex pheromones caused them to run down.

These data are c o n s i s t e n t with my convec t i ve model for v o l a t i l e

pheromones.

In c o n c l u s i o n , the v e r t i c a l d i s t r i bu t i on data , p red i c tab l e nocturnal

m i e r o m e t e o r o l o g i c a l p r o f i l e s , pheromone d ispers ion models , male

o r i e n t a t i o n b e h a v i o r , and labora tory experiments suggest that

i n t r a s p e c i f i c he i gh t s t r a t i f i c a t i o n in these species o f cockroaches i s a

mechanism that enhances the e f f i c i e n c y o f the mate-f inding p rocess .

97

t e c h n i c a l a s s i s t a n c e with the temperature g rad i en t , W.J. Bell and R.

Shaw f o r c r i t i c a l read ing o f the manuscript, and F.W. Fisk for

i d e n t i f y i n g voucher specimens. Supported by NSF grants BNS 80-06284 and

BNS 77-24898 t o W.J. Be l l and DEB 80-07556 to WJB and me. This work,

w i th some m o d i f i c a t i o n s , was published in Science 215: 1405-1407 (1982).

Copyr ight by the American Assoc ia t i on for the Advancement of Science.

98

F i g u r e 4 - 1 . Temperature p r o f i l e s f o r a t y p i c a l 24 hour per iod in the

d r y season (10 A p r i l 1980 ) . Mercury thermometers were posi t ioned at

f our h e i g h t s in the under s t o r y . Measurements were recorded every 2

hours a l ong w i th c l i m a t o l o g i c a l c o n d i t i o n s . The s t ipp l ed area

r e p r e s e n t s n i g h t t i m e .

99

Time

E

o

E?

I

18 22 26 30

T e m p e r a t u r e ( °C )

100

ure 4-2 . Wind p r o f i l e for day and night condit ions in the dry

season. Instantaneous readings with an Alnor type 8500

Thermo-anemometer were taken every 15 seconds for 4 minutes at each

o f three h e i g h t s , fo l lowed by e i gh t addit ional readings at each

he i gh t . The sampling order o f the three heights was randomized; 96

instantaneous read ings taken over 4 days were averaged ( ± standard

e r r o r ) for each h e i g h t .

102

ure 4 -3 . Titanium t e t r a c h l o r i d e was used as point sources for smoke

plumes. The photograph (A ) was taken at 2 p.m. Note the

predominant ly h o r i z o n t a l f l ow at both po int sources. The photograph

(B ) was taken a t 11 p.m. Nightt ime unstable condit ions r e s u l t in

v e r t i c a l ascent from the lower source (10 c m . ) .

104

CHAPTER 5

Eco log i ca l Correlates of Paternal Investment of Urates

in a Tropical Cockroach

Females o f the t rop i ca l cockroach Xestoblatta hamata feed on urates

o f f e r ed by the male a f ter copulation. Females on nitrogen-def ic ient

d i e t s inges t and transfer to their maturing oocytes more male-derived

ur ic acid than do females on high-protein d i e t s . In iso lated females,

the g r ea t e s t uptake o f uric acid by the ova r i e s occurs during the mating

stage in the reproduct ive cyc le . Uric acid from males contributes

s i g n i f i c a n t l y to the female 's nitrogen pool and may help shorten the

time between mating and ov ipos i t i on . In both f i e ld and in laboratory

experiments males choose high-protein foods and dietary uric acid.

105

INTRODUCTION

Cockroaches, unl ike many t e r r e s t r i a l i n s e c t s , void l i t t l e ur ic acid

( M u l l i n s and Cochran, 1972). Instead, they s to re urates in spec ia l i zed

c e l l s o f the f a t body or secre te them into accessory glands in males o f

some s p e c i e s . In three subfamil ies o f cockroaches the male coats h i s

sperm package with ur ic acid a f t e r inser t ing i t in to the female (Roth

and Dateo, 1964, 1965). Roth (1967» 1970c) suggested that uric acid might

p r o t e c t the spermatophore from being prematurely consumed by the female

or by other i n s e c t s , and Cornwell (1968) suggested that i t might ac t

l i k e a plug to prevent females from mating repea ted ly . Mullins and Kei l

(1980) r e p o r t e d , however, that the sperm ato phore-ur ate complex sometimes

disappeared sho r t l y a f t e r mating and that male uric acid could be

recovered from mated B l a t t e l l a germánica females and the i r oothecae.

The t r ans f e r o f urates was re la ted to the nu t r i t i ona l state o f the

f ema l e : those on a low-pro te in d i e t t rans ferred more to oothecae than

did those on a h igh-prote in d i e t . Mullins and Ke i l (1980) suggested

tha t the t rans fe r o f urates might represent "paterna l investment o f a

n i t r ogen resource from which the female and her progeny might b e n e f i t . "

I r epo r t a post-copulator y behavior in the t r op i ca l r a i n - f o r e s t

cockroach Xestoblat ta hamata that supports the paternal investment

p roposa l . A f te r copulat ion the male r a i s e s h i s wings, t e l escopes h i s

abdomen, widens the g en i t a l chamber exposing a white urate s e c r e t i on ,

and d i r e c t s i t toward the female (F i g 5 - 1 ) , who ingests the s e c r e t i o n .

This behavior supports the nu t r i t i ona l investment hypothesis and Mull ins

and K e i l ' s (1980) suggestion that the male urates are ingested by the

106

f emale ( B ^ germánica in the i r r e p o r t , subfami ly B l a t t e l l i n a e , as i s

hamata) . This cockroach spec i es i s one o f few f o r which s u f f i c i e n t

e c o l o g i c a l data a r e - a v a i l a b l e ( s e e Chapters 3 ,4 ) to d i r e c t l y assess the

s i g n i f i c a n c e o f male d i e t a r y c on t r i bu t i ons t o the f ema l e ' s n i t r ogen

budge t .

RESULTS and DISCUSSION

Both the s i z e o f the maleas u r i cose g lands and the d i e t a r y n i t r ogen

s t a tus o f the female determine the durat ion o f f eed ing and the quant i ty

o f u r i c acid ingested by the f ema le . I maintained sane females on an 8

percent case in prote in d i e t , and o thers on a 64 percent casein d i e t : in

males the r e s u l t was small (mean± S.E.M., 1 3 . 0 ± 1.5 mg; N=9) and l a r g e

( 2 7 . 4 ± 1 . 2 mg; N=11) ur icose g l a n d s , r e s p e c t i v e l y , a f t e r 20 days . Long,

uninterrupted post -copulatory f eed ing was common when the male had l a r g e

s t o r e s o f urates r ega rd l ess o f the n u t r i t i o n a l cond i t ion o f the female

(poo led data for both female groups : 216-5 ± 1 9 * 2 3 seconds, 2.3 ± 0.33

pauses; N=11) . Females d e f i c i e n t in d i e t a r y n i t r ogen (N=5) continued to

pa lpate the male and attempted t o feed a f t e r h i s small gland was

d e p l e t e d . Hence, the i r cumulat ive feeding pe r i ods were s i g n i f i c a n t l y

l onge r than those o f females with high d i e t a r y n i t r o g en (N=7 ) : 128.0

±22.73 seconds, 4.0 ±0.45 pauses, versus 76.4 ±12.66 seconds, 2.9± 0.40

pauses (P<0 .05 f Mann-Whitney U - t e s t ) .

Females maintained on the l ow-pro te in d i e t incorporated and

t rans f e r ed to t h e i r egg-cases l a r g e q u a n t i t i e s o f l a b e l which had been

i n j e c t e d in to males as [8 - C ] -hypoxanth ine , whether the males had

107

small or l a r g e ur icose g lands ( Tab l e 5 - 1 ) . Females on a h i gh -pro t e in

d i e t acquired s i g n i f i c a n t l y l e s s l a b e l from males with l a r g e u r i c ose

g lands ( t=3 .53> P=0.008) and consequently incorporated l e s s l abe l i n t o

t h e i r oothecae ( t =8 .67 » P=0 .003 ) . Some l a b e l was l o s t in the t r a n s f e r

o f u r i c a c i d . I d id not quant i fy the conversion o f hypoxanthine to u r i c

1 4

acid nor measure urate metabolism t o CO>. In Parcoblat ta the amounts

14

o f evo l ved are r e l a t e d to n i t rogen content in the d i e t (D.G.

Cochran, personal communicat ion) .

Transfer o f ur i c acid in to the terminal oocytes beg ins a f t e r the

th i rd n i gh t o f an 8- t o 9-day ovar ian c y c l e ; mating usual ly occurs on

the fourth n i g h t . As both the pro te in content (due to uptake o f blood

v i t e l l o g e n i n ) and th e mass o f the o va r i e s i n c r eas e , the percentage o f

n i t rogen content remains r e l a t i v e l y constant ( 8 . 4 7 * 0 . 5 1 p e r c e n t ) . Y e t ,

ovar ian ur i c ac id ( u r i c a s e assay ) increases from 3.4 jig per mi l l i g ram o f

dry ovar ian t i s sue e a r l y in the c y c l e to 61.7 jig per mi l l i g ram o f dry

t i s s u e when o vu l a t i on beg ins ( F i g . 5 - 2 ) . Hence, the percentage o f

t o t a l ovarian n i t rogen a t t r i bu t ed to ur ic acid increases from 1.0

percent immediate ly a f t e r d epos i t i on o f an egg case (day 1) t o 27*7

percent in mature oocy t es ( F i g . 5 - 2 ) .

A s im i l a r pat te rn was observed by incorpora t i on o f l abe l ed 1 4

hypoxanthine in the o v a r i e s . I i n j e c t ed 1 yl o f [8 - C]-hypoxanthine

in to females on the f i r s t day o f the ovarian c y c l e ( p o s t o v i p o s i t i o n ) and

assayed the r a d i o a c t i v i t y o f paired ova r i e s on subsequent days . The

r a d i o a c t i v i t y was 352 ±32 dpm on day 2 (N=3) » 5170± 1200 dpm on day 4

(N=4) , and 10,479 ±1148 dpm (N=3) on day 6. The females were maintained

on a 25 percent p ro te in d i e t .

108

Females mate r epea t ed l y throughout t h e i r adul t l i v e s e i the r because

o f sperm shortage or because o f urate d e f i c i e n c y . The l a t t e r i s

impl icated by the f o l l ow ing da ta : females maintained on a h i gh -p ro t e in

d i e t produced egg cases conta in ing s i g n i f i c a n t l y more ur ic acid than

females on an 8-percent pro te in d i e t (7 .6 ± 1.01 MM and 4.8 ± 1.00 /! M per

egg c a s e , corresponding t o 2.58 and 1.52 percent o f the dry w e i g h t s ,

r e s p e c t i v e l y ; N=8, P=0 .01 ) . Two f r e s h l y deposi ted oothecae c o l l e c t e d in

the f i e l d y ie lded an average o f 7.3 ¿¿M ur ic a c i d , suggest ing t h a t , in

the f o r e s t , females may feed on h igh-pro te in f o o d s , on ur ic a c i d , or on

bo th . Ye t , f i e l d ev idence i nd i ca t e s tha t females feed on

n i t r o g e n - d e f i c i e n t foods and r a r e l y fo rage on ur ic a c i d . In cho i ce

experiments in the l abo ra t o r y h igh-n i t rogen d i e t s were consumed mainly

on n i gh t s 3 and 4 o f the ovarian c y c l e . Foods (mainly p lant m a t e r i a l ;

Chapter 3) ingested at t h i s stage in the f i e l d contained more n i t r ogen

than did foods consumed during e a r l i e r and l a t e r s t ages , but the

n i t r ogen content was not s u f f i c i e n t to produce the 7 #M o f ur i c acid

found in egg cases c o l l e c t e d in the f i e l d (data not shown) .

As in the German cockroach, but unl ike the American cockroach, X.

hamata females use most o f the food consumed be fore o v i p o s i t i o n for a

s i n g l e egg case ; l i t t l e nu t r i en t s torage occurs (E^ germánica females

use 90 percent o f the food gained in the p r e o v i p o s i t i o n a l period for the

product ion o f a s i n g l e egg case [Kunkel , 1966 ] ) . Moreover, in the

f i e l d , the uric acid content ( o v a r i e s and stomachs exc luded) o f

p o s t o v i po s i t i on females did not d i f f e r from females midway through the

ovar ian c y c l e ( 1 1 . 51 ± 4.75 jiM and 1 2 . 2 3 * 3 . 9 1 M m P e r female f which

represent 1.54 and 1.16 percent o f the t o t a l dry we ight , r e s p e c t i v e l y ;

109

N = 10, P=0 .89 ) » and some females in both goups had low ur ic acid

r e s e r v e s . An increase in ur i c acid content through the f i r s t 4 days o f

the ovar ian c y c l e should occur i f females ingested foods high in

n i t r o g e n .

The percent ur ic acid va lues which I r epo r t are s i g n i f i c a n t l y lower

than the 18 t o 87 percent va lues reported for female germánica

(Va lovage and Brooks, 1979) » and the 8 t o 31 percent reported f o r

var ious spec i e s maintained in the l abo ra t o r y (Mul l ins and Cochran,

1976) . Potr ikus and Breznak (1980) reported that f r e s h l y c o l l e c t e d

t e r m i t e s contained approximate ly 2 percent uric a c i d ; the amount

increased t o 45 percent for those in c a p t i v i t y , ind i ca t ing tha t l e v e l s

o f ur i c acid might g e n e r a l l y be higher in c a p t i v e cockroaches as w e l l .

The average dry weight o f ur i cose glands in a natural population was

17.6 ± 1.2 mg (N=45) which, i f one assumes a urate content o f 4.3 per

m i l l i g r am o f dry gland as repor ted for B^ germánica and Nyct ibora l u t z i

( M u l l i n s , 1979)» corresponds t o 75-7 MM o f ur ic a c i d . I did not

determine the urate content o f Xestob la t ta ur icose g lands . The average

male has s u f f i c i e n t ur i c acid in h is ur icose gland to supply enough f o r

10 egg c a s e s , i f there i s no l o s s during t rans f e r and uptake by the

f ema l e . Since oothecal ur ic acid i s r e l a t ed to d i e t a r y n i t r o g en , and i f

embryonic ur ic acid increases the f i t n e s s o f the young, females would

have to fo rage for h igh-n i t rogen foods to obtain adequate quan t i t i e s o f

u r i c acid in the absence o f ma l e s .

My data ind i ca te that i f females have access to ur ic acid a f t e r

mat ing , the preov i p o s i t i o n a l per iod may be shortened. Since de lay ing

o v i p o s i t i o n may r e s u l t e i t h e r in r esorp t i on o f oocy tes i f e s s e n t i a l

110

n u t r i e n t s are not a v a i l a b l e ( B e l l and Bohm, 1975) or in re-mating f or

bo th , the male should minimize the time between mating and o v i pos i t i on .

^ J*!_ germ an i ca when two males mate with a female be fore she o v i p o s i t s ,

mixing o f the two e j a c u l a t e s ( t ha t i s , sperm compet i t ion) may occur

(Cochran, 1979) •

Presumably, these consequences o f d e f i c i e n c y in nitrogenous f oods ,

short r ep roduc t i v e c y c l e s , a concurrent demand by females for other

n u t r i e n t s , and the r e l a t i v e s c a r c i t y o f foods high in n i t rogen would

s e l e c t f o r male urate con t r ibu t i on to females . Although males have

r e l a t i v e l y low n i t r ogen requ i rements , they feed on bird and r e p t i l i a n

droppings ( F i g . 5-1C) which are l a r g e l y ur ic a c i d . In cho ice

experiments in the l a b o r a t o r y , males consume l a r g e percentages o f ur ic

acid and h i gh -p ro t e in food which r e s u l t s in rapid enlargement o f t h e i r

ur i cose g l a n d s . Y e t , i f s exua l l y r e c e p t i v e females are not a v a i l a b l e to

accept the accessory s e c r e t i o n , accumulation o f e x t r a c e l l u l a r ur ic acid

r e s u l t s in increased m o r t a l i t y (Haydak, 1953)- Mull ins and Cochran

(1973) repor ted t h a t mutagenic and carc inogen ic tryptophan metabo l i t es

increase as d i e t a r y n i t r ogen i n c r eases , and they suggested that the

qu ino l ine compounds contr ibuted to the increased m o r t a l i t y o f P.

americana on h i gh -p ro t e in d i e t s .

Pressures on the male to accumulate and void stored urates and h i s

enhanced f i t n e s s when ur i c acid i s success fu l l y t rans ferred to the

female may have cont r ibuted to the evo lu t i on o f a r e l a t i v e l y protracted

copu la t i on (248.3 ± 1 8 . 5 minutes ; N=9 ) . Other spec i es o f cockroaches

copulate for about 20 t o 120 minutes ( e . g . , Stay and Roth, 1958). This

per iod in X_*_ hamata approx imate ly corresponds to the time required for

111

the crop t o empty f o l l ow ing f eed ing . In the f o r e s t f females feed on

p lant ma t e r i a l s t a r t i n g a t approximately 1900 hours and couple with

males a t midn ight , a l l ow ing for only one mating per n i g h t . Hence, the

male may be de lay ing the depos i t ion o f a spermatophore unt i l the

f ema l e ' s c rop i s empty and she can accomodate h i s urate s e c r e t i o n .

Parker (1970) suggests that long mating s e q u e n c e s may be a form o f

mate-guarding (and pa te rn i t y assurance) whereby the female i s

unava i lab le to o ther males when she i s most r e c e p t i v e .

On the bas i s o f s i g n i f i c a n t urate accumulat ion in aposymbiotic

cockroaches , and mob i l i z a t i on o f urates by cock roaches d e f i c i e n t in

n i t r o g e n , r esearchers have implicated bac ter ia i n the degradat ion o f

ur ic ac id ( r e v i e w : Mull ins and Cochran, 1 9 7 5 ) . Spec ia l i zed c e l l s

harboring symbiot ic bacter ia are a lso found in the o v a r i e s o f

cockroaches (Brooks and Richards, 1966) and a r e t r a n s f e r r e d to oocytes

during t h e i r maturat ion . I f , in f a c t , t r a n s - o v a r i a l transmission o f

u r i c o l y t i c b a c t e r i a occurs in hamata ( a s i t does in the other

cockroach spec i es examined thus f a r ) , then n i t r o g e n and carbon may be

gained from metabolism during embryogenesis o f p a t e r n a l l y der ived ur ic

a c i d .

ACKNOWLEDGEMENTS

I thank G. Macaya o f the Universidad de Costa Rica for a l lowing me

access t o a s c i n t i l l a t i o n counter and o t h e r equipment and K.B.

Armitage, D.G. Cochran, R. Jander, C.B. K e i l , H.B. L i l l y w h i t e , C D .

Michener, D.E. Mu l l i n s , and R. Thornhi l l f o r c r i t i c a l rev iew o f the

112

manusc r ip t . Supported in part by NSF grants BNS 8 0 — 0 6 2 8 4 t o W.J. B e l l

and DEB 80-07556 t o WJB and rae, and a Sigma XL Gran t - i n - A i d o f Research

t o me. Th i s c h a p t e r , with some mod i f i c a t i ons , w a s pub l i shed wi th

W i l l i am J . B e l l as co-author in Science 218 :170 -173 ( 1 9 8 2 ) . Copyr ight

1982 by the American Assoc iat ion for the Advancement o f* S c i e n c e .

113

Table 5-1 • Fate o f l abe l ed hypoxanthine in jec ted in to males .

Males wi th empty u r i c o s e g lands were in j ec t ed with 1 Ml

14 [ 8 - C]-hypox an th ine and maintained on 8 or 64 percent prote in d i e t s f o r

14

8 t o 30 days . The C- labe led urates were traced in males , mated whole

f ema l es , and in egg cases by the e x t r a c t i on and counting procedures o f

Mul l ins and K e i l ( 1 9 8 0 ) . The amount o f l a b e l incorporated into the

accessory gland increased with t ime ( y = 6900 + 3 0 0 0 x ) . Only

copu la t i ons occurr ing 20 t o 25 days a f t e r i n j e c t i on are r e p o r t e d .

Uricose g lands o f unmated males averaged 114,606 ± 19.207

degradations/min per male ( N = 7 ) ; the average for the r e s t o f the body

was 11,327* 588 dpm (N=7) a f t e r 20 t o 25 days . The r e l a t i v e l y l a r g e

var iance in the r a d i o a c t i v i t y o f females in the group on the 64-percent

pro te in d i e t with access t o l a r g e ur icose glands was in part due to

d e f e ca t i on o f u r i c acid s h o r t l y a f t e r i n g e s t i o n . Two white f e c a l

p e l l e t s from two females in t h i s group contained 25,817 and 33»511 dpm

per i n s e c t .

Each e n t r y r epresents a mean, standard e r ror o f the mean, number o f

o b s e r v a t i o n s , and c o e f f i c i e n t o f v a r i a t i o n .

S i gn i f i c ance va lues are based on t - t e s t s .

/-> LO LO LO LO

CM CM 5 ^ CM 5 ^ P O • 00 VO • rH CO ^ rH • rH rH rH O) +1 00 +1 00 +1 00 +1 LO

Pí *+H rH rH rH • ON rH CO CM o • • "W o

LO ll CO rH rH Ph rH rH cu Ph

rH CO /—\ / " ^ /—\ a m LO LO LO

<U rH l o ^ o s-s O cu CO T3 • rH • 00 • vO • CM P O tí co « <f . 00 VO • CO U CO +1 VO rH +1 +1 LO

% H JH l o • < r co en • O . v—'

o P CN o II LO 00 rH CM Ph 00 X

/~N • /—\ «\ rH

E CM CM v / • w y—S

rH cO O 5 ^ TJ ü « • 00

* 0 tí CU rH • CM • O * o x ! +1 LO • ü .p 00 rH en cm en CO CU O •

• cu GQ O LO CT\

tí rH CO CO /-N / ~ \ /—s

•H CO CM CO -p V /—\

CO < ¡ ^ rH 3 ^ vü X I P ü • vO • 00 U CO CU CM • CM * LO O rH o • 03 5-1 X I +1 O rH +1 • +1 o O CO •rl -P m CM as cm • r - on. LO co u cu to o • • v / O

M o CM II 00 CM

U cO CM rH Oh O £ O CU

to /—•n

tí to /•—\ LO /*-\

•H l o LO w LO CU CM / - n

CO O 3 ^ r - ^ •P CO O) CU • CM * CM 00 O LO • <f

rH rH LO • LO * rH rH <r .

> O CO +1 + i LO +1 oo •hi <r •H X I s CM rH rH rH • CO CO LO LO •P 15 CU • s—• O • v v U m en II as CJN cO Ph LO rH O

•H

CO CO CU P* CU "O • rH <u rH CU P*

rH tí rH 00 rH OjO CO CO • co CO p a rH £ cO s co

CO co rH

CU CO e CU to

.p cu

•H H3>

00 cu

o u vO

tí •H cu P o u

CM VO

o II

Ph

CM O O

o II

Ph

CO o o

o II Ph

00 o o o II Ph

117

ure 5 -2 . To eva luate the t ime-course o f the uptake o f ur ic a c id , the

o v a r i e s o f f i e l d , captured females were assayed enzyraat ical ly

(u r i case t e s t ) f o r ur ic acid content . Percent n i t rogen at t r ibuted

to ur ic acid was ca l cu la t ed on the bas i s o f 33.3 percent n i trogen in

ur ic a c i d . Po in ts r epresen t the average o f two r e p l i c a t e s o f

seve ra l o va r i e s each .

118

Day of Reproductive Cycle

119

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